Form refers to the pattern (or plan) of individual sections of music within a song. The most common section lengths are 4 or 8 bars. One of the most common types of form is called binary form, where the order of the sections is A B. Sometimes these sections are repeated (e.g., AA BB), but the basic binary form is maintained.
A simple example of form in modern music is the verse/chorus relationship found in most songs. You should always determine the form of a song, as this will make it easier to learn.
Bm
This arrangement features the melody as the top note of each chord. It is in binary form, containing two 8-bar sections, which can be further broken down into four 4-bar phrases. You should practice each 4 bar phrase separately, analyzing the chord shapes and fingerings before attempting to play the whole song.