Conditional formating depending on value

Welcome to the forum.

Select the cell with the formula =IF(K31>24,"FULL","AVAILABLE")

In Conditional Formatting, New Rule, Use formula.... enter this formula:
I have used M1 for the cell with the formula for this example:

Formula:

=M1="FULL"

Choose the formatting that you want for full. Click OK, Apply and click OK.

With M1 still selected enter the following in Conditional Formtting, New Rule, Use formula...

Formula:

=M1="AVAILABLE"

Choose the formatting for AVAILABLE. CLICK, OK, APPLY, OK.

In this very simple example (only 2 cells used) change the value in K31 and see the colour change in M1