If you love music and want to learn to play an instrument or learn about music theory, you could definitely benefit from one or more music workbooks. A place like C.R. Carol has selections to get you started. Whether you are a beginner or at intermediate level and beyond, there is always somethings new to learn. The more knowledge you gain, the better you will be able to transfer that knowledge into music that others will enjoy and appreciate.
For beginners, these books typically start with the basics with things like the staffs and the difference in the treble and bass clefs. If the piano is your instrument of choice, this is how you distinguish what is played with the right hand vs. what is played with the left. If you are a guitar player, you will only be concerned with the treble clef. The bass guitar player will pick up the notes from the bass clef.
Once you understand the basics about the clefs, you will go on to learn about the notes that are written on those clefs. This is where things start to get a bit more challenging for the beginner. While it can be quickly figured out what those notes are by using some memory techniques, what is important is to be able to recognize them without having to think about it. From that standpoint, it can be similar to what it was like when you learned the alphabet. You had to think about what each letter looked like. Now, you think nothing about that as you see letters connected together on paper to form words. The only answer to having the music notes come that naturally is practice. Though it may be frustrating at first, if you keep working at it, you will get past the frustration stage and advance to the point where it becomes enjoyable and relaxing.
After you get the notes somewhat memorized, you will need to begin working on timing. This means learning the difference in things like quarter and half notes. If you have the notes right, but the timing is wrong, you will not be playing anything that resembles the song you were intending to play.
By using these tools to learn music, you can advance as far as you want to go. If you only intend to use music for your own enjoyment, that is fine. If you plan on going on to make a career from music, that is also fine. The beautiful thing about music is that it can be enjoyed at many different levels.