This lines you indicated are written in Iambic/Dactyl Tetrameter. Dactyl refers to the poem's meter - the pattern of syllables in a line. Dactyl consists of two unstressed (or weak) and one stressed syllable. Each of the lines here start with a iamb - one unstressed and one stressed syllable, followed by two dactyls.
The tetrameter refers to the number of meterical feet in each line. There are three in these lines - one iamb, and two dactyls.
The shorter two lines also start with an iamb and then a dactyl, but the last foot of those lines is not completed.