To be able to attend college in the USA, schools usually requre to take the SAT (Scholastic Aptitude Test or Scholastic Assessment Test) or the ACT (American College Testing).
The SAT has 3 different sections: verbal, math and writting while the ACT has also a science section. The math skills required for either test are no more complicated than the ones students have during regular high school in most countries in the world. The verbal section, however, could be more challenging specially for those students for which English is not their native language.
The TOEFL (Test of English as a Foreign Language) is only required for those students whose native language is not English and you can see more details about the test on the International students section.