Question

Why is this verse an example of iambic pentameter?

Answer 1

Well, you didn't provide us with the verse, but I can still explain what an iambic pentameter is.
It is a type of a line that Shakespeare always used in his poems and plays. Iambic refers to the sequence of stress in syllables - the first syllable is always unstressed, and the second one is stressed, and so on in the entire line. Pentameter refers to the number of syllables in each line, which there are 10. Penta in Latin means 5, meter consists of 2 syllables, so 5*2 = 10.