The tense in the 'if' clause is the past perfect, and the tense in the main clause is the present conditional:
If + past perfect
If I had worked harder at school
If we had looked at the map
I would have a better job now.
we wouldn't be lost.
In these sentences, the time is past in the 'if' clause, and present in the main clause.
They refer to an unreal past condition and its probable result in the present.
They express a situation which is contrary to reality both in the past and in the present:
'If I had worked harder at school' is contrary to past fact - I didn't work hard at school, and 'I would have a better job now' is contrary to present fact - I haven't got a good job.
If we had looked at the map (we didn't), we wouldn't be lost (we are lost).
The tense in the If-clause is the simple past, and the tense in the main clause is the perfect conditional:
If + simple past
If I wasn't afraid of spiders
If we didn't trust him
I would have picked it up.
we would have sacked him months ago.
In these sentences the time in the If-clause is now or always, and the time in the main clause is before now.
They refer to an unreal present situation and its probable (but unreal) past result:
b. I'd have been able to translate the letter if my Italian was better.
c. If I was a good cook, I'd have invited them to lunch.
d. If the elephant wasn't in love with the mouse, she'd have trodden on him by now.
He doesn’t have a very good job. (present)
This sentence shows the present consequences of a past action.
She isn’t going to
This sentence shows the future consequences of a past action.