This poem is in standard Habbie, also known as the Burns stanza. It is a six-line stanza rhyming aaabab. Lines 1, 2, 3, and 5 are in tetrameter (4 strong beats or accents per line), while lines 4 and 6 are in dimeter (2 strong beats or accents per line).
Of course, the more remarkable thing about the poem is Burns' use of the Scots dialect, which makes some of the rhymes more interesting. Also, the fact that so many of the lines in the stanza rhyme with each other serves to emphasize the rhyme.