AND and OR take several tests and return TRUE or FALSE:
=AND(B2>=4,C2>=2) is TRUE only when every test is TRUE.=OR(B2>1000,C2="VIP") is TRUE when at least one test is TRUE.
On their own they show TRUE or FALSE, which is handy for quick checks such as "is this value between 2 and 8?": =AND(B2>=2,B2<=8).
Most of the time you put them inside IF as the test: =IF(AND(B2>=4,C2>=2),"Yes","No"). Read it from the inside out: AND decides TRUE or FALSE, then IF picks the result.
Text in a test goes in quotes and isn't case-sensitive, so C2="vip" also matches VIP.