The rhyme scheme is typical of the English, or Shakespearean, sonnet: abab cdcd efef gg. This means that the last words in lines 1 and 3 rhyme (this is called end rhyme), the last words in lines 2 and 4 rhyme, the last words in lines 5 and 7 rhyme, the last words in lines 6 and 8 rhyme, the last words in lines 9 and 11 rhyme, the last words in lines 10 and 12 rhyme, and then the last words in lines 13 and 14 rhyme (this pair is called a rhyming couplet).
In line 1, the word "minds" is substituted for entire people (it isn't our "minds" that get married, but ourselves); this kind of part-for-whole substitution is called synecdoche. Love is compared, via metaphor, to "an ever-fixed mark" that is not shaken even by storms. Another metaphor compares love to a "star" that guides travelers home. Love is personified, as is Time, made capable of being a fool (though it isn't one) or having a fool, respectively. Time is also personified as a reaper, who takes our years and our "rosy lips and cheeks" away. These qualities stand in for our youth, and this kind of detail being substituted for a thing with which it's associated is called metonymy.