Excel tests for multiple conditions using the IF function. The function is defined as IF(test, true_value, false_value). You can find many examples in the Excel Help for the IF function.
You must use concatenated if ... Suppose you have a condition like cond1 and cond2, you can use =if(condition1;if(condition2;true;false);false)
condition1 or condition2 => =if( condition1;true;if(condition2; true; false ) )
Multiple conditions you can have with nested if statements. You can write something like =IF(B1=1;A1;IF(B1=2;A2;IF(B1=3;A3;""))). If you do not have an english version you have to translate the IF.
To combine, e. g. , comparisons you can use AND and OR functions. For instance, =AND(A1>0,B7<8) means that both the value in the cell A1 should be positive and the value in the cell B7 should be less than 8.