Tracks are selected by clicking on the Track header at the left of the Editor window. You can select multiple tracks with Left clicks, or a range of consecutive tracks with Left.
By default, selecting regions has no impact on track selection. You can select a track, then select a region in another track (or vice versa) and both selections will co-exist happily. Operations that are applied to tracks will use the track selection, and those that apply to regions will use the region selection. Similarly, deselecting a region will not deselect the track it is in (if that track was selected).
In some workflows, and particularly if you have experience with other DAWs, this is not the most comfortable way to work. You may prefer to work in a style where selecting a region will also select the track that the region is in. Similarly, when the last selected region in a track is deselected, the track will also become unselected.
To control this behaviour, set Edit > Preferences > Editor > Link selection of regions and tracks.