Historically, the 2.4 GHz frequency is the most commonly used to connect Wi-Fi devices, which is why it's also the most congested. It’s a kind of base network (e.g. Videotron1234).
If your device is compatible with the 5 Ghz network, its performance will likely be better on that frequency. In order to establish a connection via the 5 GHz frequency, look for a network of the same name, but with “_5GHz” or “_Media” tagged on at the end (e.g. Videotron1234_5GHz, Videotron1234_Media).
While the two network names and the password may differ from one network to another, the basic configurations are the same for both.