Solved
I put this trigger to trigger only when specific column value changes.
It's working...
@not(equals(triggerOutputs()?['body/OData__x0031__x002e_ServiceStart/Value'], null))
@equals(triggerOutputs()?['body/OData__x0031_Emailsent'],false)

to create condition, simply follow this steps;
1.

2.

3.
here select column value (if this value changes, the flow shell trigger)

select "Edit in advance mode

copy this and remove in null comma
and pest to trigger condition.

It works like,
1st email trigger when
in
column "1. Service start" we change value to "service start"
and
column "1. Email SS" should be empty means false

then
flow update item in SharePoint
column "1.Email SS" change to True (so It doesn't trigger again)
2nd email trigger when
in
column "2. BAU communication" we change value to "BAU communication"
and
column "2. Email BAU" value is empty means false

then
flow update item in SharePoint
column "2. Email BAU" change to True (so It doesn't trigger again)