Disclaimer, there are hundreds of scales you could learn but you only need five to be able to play, create and improvise most types of commercial and popular music.
As a novice musician, scales can seem boring and somewhat useless in the initial stages. The truth of the matter is, without scales you'll never progress and will only be able to accomplish basic rhythm playing. Scales allow you to play iconic riffs, licks, solos as well as improvise and create your own melodies and hooks. One of the best ways to learn and practice scales is with a loop pedal. They allow you to break out of a boring rudimental practice regime and venture into a creative head space, which is how they're intended to be used. With all that said, you really only need five scales to be able to play most music. The big exception here would be for jazz and classical music, but even these scales can still be applied for those genres.
The major scale is the basis of all music theory – it is used when a composer wants to depict happiness, hope and joyful emotions. In order to be able to recognise and play a major scale you need to understand its construction. The major scale is a diatonic scale with half steps between the third, fourth, seventh and eighth degrees, and whole steps between the other remaining degrees.
The natural minor scale is essentially the major scale but starting on the sixth degree of the key, and not the one (tonic). This makes a lot more sense later on when delving into modes. The minor scale contains half-steps between 2-3rd and 5-6th scale degrees. The Natural Minor has a sad quality to it making it the go to scale for melancholic and darker music.
The main difference between the major scale and the major pentatonic is the major scale has 7 notes, while the major pentatonic only has 5. To derive the major pentatonic scale from the major scale, simply remove the 4th and 7th degrees, which leaves you with five notes per octave. The pentatonic scale contains the most commonly used pitches in many popular songs. Its lack of half-steps contribute to its distinctive sound, as compared to a major or minor scale. It's often the first scale guitarists acquire as its very easy to learn and quick to utilise.
The main difference between the minor scale and the minor pentatonic is you guessed it, 5 notes over 7. The minor pentatonic scale is made from the 1st, 3rd, 4th, 5th and 7th notes from the natural minor scale. The 2nd and 6th notes of the minor scale are therefore not used. The minor (and major) pentatonic is used in music from all types of cultures all over the globe, and is called the most universal of scales because of its ubiquity.
The Blues scale is the final scale on this list for a reason. If you decide you want to take all of this further and expand your scalic knowledge, the blues scale is a good starting point. Its origins come from 'Blues' music as described in the title and its use has helped shape the culture of jazz, soul, funk and more. A blues scale is a six note scale based on the major or minor pentatonic with added chromatic “blue” notes. The blue notes are ♯ 4/♭5 in the minor blues scale, and ♭3 in the major blues scale.
Once you've truly explored all these scales in all 12 keys, I'd then progress by learning how to extend their range on your instrument of choice. Using the same scale but over a wider octave range will inspire new ideas and open more technical possibilities within improvisation and mastering your instrument. Below are some fretboard diagrams for guitarists, but you can still construct the scales using the interval degree information above.