What should be the narration for recording annual depreciation? i.e. Depreciation Exp. And Accumulated Depreciation

Your accounts are Depreciation Expense and Accumulated Depreciation.

Your journal entry will be:
Debit Depreciation Expense for the amount of depreciation
Credit Accumulated Depreciation for the same amount

This entry is used to match expenses to revenues in the period they occurred or were earned.

Depreciation Expense is an expense account and Accumulated Depreciation is a contra asset account, which means is offsets an asset which will be a PP&E account.