Hi @Vanessa_0612
Pls try using expression for the left part of the condition. Expression needs to be added in the expression box as shown below:

first(outputs('Run_a_query_against_a_dataset')?['body/firstTableRows'])?['CountALERT_CHECK']
EDIT (Revised Expression):
first(outputs('Run_a_query_against_a_dataset')?['body/firstTableRows'])?['[CountALERT_CHECK]']
If this helps & solves your problem, please remember to give a 👍 and accept my solution as it will help others in the future.
Thanks