Some jurisdictions tend to favor non-compete agreements, others hold most of them to be unenforceable. From a very quick search, BC is a little reluctant to enforce them, but they can be valid if sensibly drawn.
However, the text you included in the question is not a non-compete agreement at all, it is a non-solicitation agreement, a much less restrictive agreement, which is significantly more likely to be upheld.
The agreement quoted in the question does not mandate the employee continuing to work for the employer for any minimum time, not two years, and not six months. (Another provision might specify a required notice period, but that was not quoted and may not be in the agreement.)
The agreement quoted does not prohibit the employee, after s/he leaves the job, from working for a competitor of the former employer, not even for a brief period.
What the agreement quoted does do, is prohibit the employee from asking individuals and businesses who were customers of the former employer for orders for the same products as are sold by the former employer. This applies to orders on behalf of the employee personally, on behalf of a new employer, or on behalf of a business in which the employee has some sort of ownership stake (such as partner or shareholder). That is all that the quoted language prohibits.
This means that the employee cannot ask those who were customers of the old employer, to buy from or through him, the same products that the old employer sells. It does not mean that the former employee cannot sell such products, if the inquiry comes from the customer.
This sort of agreement is primarily aimed at preventing a salesperson from taking a client list with him or her to a new employer, and trying to get them to move their business from the salesperson's old employer to his or her new employer or business. If the employee is primarily an instructor and does not also act as a salesperson, this agreement will have almost no effect on him or her.
This site discusses such agreement an myths about them in BC, Canada. It says:
Non-competition clauses can be enforced by courts in BC. It is true that employers face an uphill battle in getting a judge to agree to enforce a non-compete, but it can and does happen. If you are wondering whether your non-compete will stick, ask an employment lawyer. Enforceability of a non-compete depends on the specifics of the wording of the clause itself and the overall employment contract. Some key considerations are whether the clause is clearly worded, and whether it is limited in time, geography and scope of what is covered.
If a non-competition clause is enforced by a judge, it will only be applied to prevent the employee from the specific activities listed. If the employer has missed something from the clause, or there is a “loop-hole,” that is generally fair game.
Many contracts include non-solicitation (aka non-solicit) clauses, which are meant to prevent the employee from contacting clients. Non-solicitation clauses are still an uphill battle to enforce, but slightly easier than a non-competition clauses. This is because non-solicits don’t dictate where an employee can work, just what business they can seek out. Even if there is no contract, obligations to respect confidential information, and fiduciary duties (in the case of key employees) last beyond the end of employment and can limit competition.
An online paper on "Is my Employee’s Non-Compete Agreement Enforceable?" by Lisa Stam says:
In Canada, courts have generally been reluctant to uphold agreements that have the effect of restricting an individual’s ability to earn a living or pursue the job of their choice. Indeed, courts take the initial position that restrictive covenants in employment agreements are unenforceable, unless the employer can demonstrate otherwise. A restrictive covenant must jump through several hoops to be deemed enforceable.
A non-solicitation agreement will allow a former employee to work for a competitor, but prevent them from soliciting the clients (and possibly the employees) of their former employer for a specific period of time. Former employees may have close relationships with clients. Allowing them to solicit these clients may give them an unfair advantage against the former employer in the marketplace. If the employee does not solicit the client, but the client leaves to follow them anyway, there is little an employer can do.
If a court finds a restrictive covenant clause unreasonable, for example it restricts solicitation for 12 months when 6 would have been reasonable, they will not read it down to fix it. Canadian courts require the employer to get it right the first time and a flawed clause will therefore normally be unenforceable.
In short, the above quoted agreement may not be enforceable. But if it is, it only restricts solicitation, not competition, and does not require the employee to work for the employer for a period of two years, or any other minimum time.