For any one interested in playing any kind of instrument or performing vocals for that manner you have to have a working understanding of basic music theory. Music theory is the basic premises for the understanding of music. This includes reading it, being able to write basic notes on the two different clefs and having a working understanding about what makes music tick.
Some of the basics that are important to understand are timing signatures, the notes on the bass and treble clef, minor and major notes and other notations which tell you such things as to play louder, softer sticcato etc. There is a musical language all its own which is important to be aware of.
Many beginner musicians get involved in their instrument and forget about the basics. When the time comes for them to learn more difficult pieces it becomes clear that not understanding these basics will be a difficulty for their continued musical advancement.
The most basic understanding of four/four time verses two/four time when playing a piece of music is imperative to understand. Simple basic theory such as knowing that in the key of “G” there is one sharp makes it so much easier to play pieces in that key.
Understanding major and minor chords and the principles that make them major or minor make it easier for you to understand true chord progressions. If you are playing a song in the key of “G” chances are you will know that know that a “Db” is not any appropriate chord in that piece, at least in most cases.
Understanding music theory will only make your job so much easier. If you do not have a working understanding of theory you might want to find someone who includes this in their overall instructions (instead of just teaching chords and strumming patterns) or get a book about it so that you can support your learning even better.