Iambic pentameter

For Iambic: According to an online dictionary: a metrical foot, line, or stanza of verse consisting of iambs.

For Pentameter: If you know a little of Greek, Penta means FIVE, Meter means Measure.

Iambic pentameter is meter that Shakespeare nearly always used when writing in verse. Most of his plays were written in iambic pentameter, except for lower-class characters who speak in prose.

Iambic Pentameter has:

Ten syllables in each line
Five pairs of alternating unstressed and stressed syllables
It sounds like this:

ba-BUM / ba-BUM / ba-BUM / ba-BUM / ba-BUM

I hope this will help you solving your doubts.