Not every employment contract is long and written by a lawyer in legal language. Some employment contracts are only a few pages, or even only one page, that spell out the key terms of your employment in very simple terms or bullet points. These contracts are perfectly legal so long as you and your employer have agreed to the terms.
For anything not stated in your employment contract, the employment standards legislation in your province, along with judge-made law from previous legal cases (referred to as “common law”), are usually what sets out what you will get at a minimum. Employment standards for example has rules about minimum wage, overtime, hours of work, vacation etc. By law, an employer cannot violate these thresholds, or offer you any less than your legal minimums, so you can assume that these laws fill in any gaps in your employment contract.
The only time that differs is when it comes to your termination pay. An employment contract has to restrict you in writing to only getting what is in the ESA if the company ends your employment. Otherwise you may be entitled to significantly more.