A portal is a common term that normally means a purpose-built website. For example, a Sales portal is a website that has specific features and content to help sales and marketing departments prepare for and engage in sales activities.
A career portal could be like monster.com, indeed.com, or dice.com. Those are just websites with a very specific set of features and serve the specific purpose of showcasing jobs or helping people with their ability to apply for and build on their careers.