So you've already read that iambic pentameter is defined as a 5-foot meter, with each foot "iambic," i.e., having 1 unstressed and 1 stressed syllable (the most common meter in English poetry) and seen the example of:
da Da / da DA / da DA / da DA / da DA)
To break it down in simpler terms,
"iambic pentameter is a rhythmical pattern of syllables. The "iambic" part means that the rhythm goes from an unstressed syllable to a stressed one, as happens in words like divine, caress, bizarre, and delight. It sounds sort of like a heartbeat: daDUM, daDUM, daDUM."
(http://www.sp.uconn.edu/~mwh95001/iambic.html)
Examples from the above source:
Here are a few examples of lines written in iambic pentameter:
"Oh, gentle Faustus, leave this damnèd art,"
- Christopher Marlowe, Doctor Faustus, 5.1.37.
"I waked, she fled, and day brought back my night."
- John Milton, "Methought I Saw My Late Espousèd Saint",
a sonnet using fourteen lines of iambic pentameter.
"But surely Adam cannot be excused,"
- Aemilia Lanyer, Salve Deus Rex Judaeorum
"We hold these truths to be self-evident,"
- Thomas Jefferson, "The Declaration of Independence"
I hope this helps you out!