Yes, these two lines are written in iambic pentameter.  Basically, an "iamb" is a term that is used to describe one unstressed syllable followed by a stressed syllable, such as when you say the word "again" - it is said as "a-GAIN" with the emphasis on the second syllable, not on the first.

"Penta" means "five", so "iambic pentameter" simply means five iambs, or ten syllables that follow the unstressed-stressed pattern.  It is particularly noticeable in everyday speech, but meter is quite important in poetry.

For your two lines, I'll write them with the unstressed words in lower-case letters and the stressed syllables in caps - there should be ten total syllables in each line:

"as AN unPERfect ACtor ON the STAGE,

who WITH his FEAR is PUT beSIDE his PART."