After watching (How to Calculate Work Days Between Two Dates in Microsoft Access. Similar to Excel NETWORKDAYS.) on youtube.

Public Function MyLeaveDays(StartLeave As Date, EndLeave As Date) As Long
Dim D As Date
Dim C As Date  
    MyLeaveDays = 0
    D = StartLeave
    C = EndLeave
    While D < C
        MyLeaveDays = MyLeaveDays + 1
        D = D + 1
    Wend
End Function

This is the code, but I want a way to get also:
if 1/2/23 < 2/2/23 then MyLeaveDays = 2 but it would only give out 1 not 2
so if the dates are equal then output 1
if the dates are two dates then output 2
else if the dates are more then output 3,4,5...etc