http://www.ehow.com/list_6075299_types-traffic-signs.html
Like in Brazil, they categorize signs as Regulatory, Warning and Informative signs (and temporary traffic control, but these
you learn almost by instinct). Just that our informative are only framed by blue contours in their edges in Brazil.

http://www.1stnevadalicense.com/course_sample.html
Very good to begginers, I crashed the car 3 times at the intersection with a semaphore (animation, worth it)...Ooops!

--------------------------

   But not so simple as that, there are plenty of legislation and traffic signals there.

When you go there, it´s advisable to call Dale or some experienced native.

  Or try some traffic education at some driver school.

   Now see some differences in signs, compared to Brazil.

http://mutcd.fhwa.dot.gov/HTM/2003r1/part2/part2c.htm#table2C4

http://mutcd.fhwa.dot.gov/HTM/2003r1/part2/part2b3.htm#figure2B19
types of yeld sign.

http://mutcd.fhwa.dot.gov/HTM/2003r1/part4/part4d.htm#section4D04C1
Flashing signal indications shall have the following meanings:
Flashing yellow—When a yellow lens is illuminated with rapid intermittent flashes, vehicular traffic is permitted to proceed through the intersection or past such signal indication only with caution.

just like in Brazil, but what about flash red, for instance?

http://www.discoverabroad.com/us/livingabroad/transportation/AmericanRoadSigns.htm
Yeld ahead different from our (see the sign above 10), see also 11 Slow down and give vehicles crossing your path their right-of-way (our "yeld" indeed)

can you say what signal is above # 24? just like our in Brazil.

So, it sounds not so simple, but with time one get´s the hang of it.