Use Len and Left to make name 3 letters

[Darlie Mary]

The last name is in Column C and the first name is in Column A. I need to
make a new column with the first 3 letters of the last name. If the last name
is 2 letters, the last letter needs to be a Z. (Example: Bo, it needs to be
BoZ). Also need to add the first initial of the first name.

 

[T. Valko]

Assuming that the last name will always be at least 2 characters long:

=IF(LEN(C1)>2,LEFT(C1,3)&LEFT(A1),C1&"Z"&LEFT(A1))

 

[Teethless mama]

=LEFT(C1&"Z",3)&LEFT(A1)