he'd

'he had'

sft M He'd had his morning cup off coffee.What is "he'd"? Is it "he had" or "he would"?

Modal 'would' can be followed only by an infinitive, have.
Auxiliary 'have/had' can be followed only by a past participle/third form, had.

Thank you! But why am I using "had" twice? When one "had" is enough--

He had his morning coffee.

Then why to say--

He had had his morning coffee?

One "had" as an auxiliary to get the past perfect tense; the other to get the required past participle of "have."

sft M Thank you! But why am I using "had" twice? When one "had" is enough--

It depends on the tense.

sft M He had his morning coffee.

This is the past simple tense.

sft M He had had his morning coffee

This is the past perfect tense. You can refer to fivejedjon's