For most of us, once you get back to the sixteenth and seventeenth century in the family tree, you will encounter Latin in record keeping. This makes deciphering the records very challenging since Latin is rarely taught today. In fact, a few of us of the "older generation" did study Latin in school many years ago, but most of us cannot recall it now.
With a small "cheat sheet" that is available online, you can translate this baptismal record:
Anno Elizabethe Tricessimo primo
Willmus filius Johis Ellingthropp decimo septimo die Nouembris
In 1589 (the 31st year of Elizabeth I's reign)
William son [of] John Ellingthrop 17th day [of] November
Bert Nelson has created a great Latin Primer page that you can use to make translations similar to the above. You can see it at http://www.xmission.com/~nelsonb/latin.htm