Scales are essential for developing finger strength and musical control. Scales practiced poorly, however, are a waste of time and will potentially hold back your musical development.
Here are SIX principles for good classical guitar scale practice.
You'll need to go a little deeper into music theory as you proceed. The best online resource for this is Guitar Theory Revolution. It recognises that music theory is very hard for guitarists because music theory has till now been located in the piano paradigm. The Guitar Theory Revolution overthrows the piano paradigm that is holding you back and embraces the attributes of the guitar to unpack music theory. In fact, it goes further and allows you to see that the guitar is one of the best instruments for learning theory.