Many a is a somewhat archaic or poetic or literary way of saying many.
Many times I had seen her in my dreams.
Note that it takes a singular complement:
Many a time I had seen her in my dreams.
EDIT
Just to throw another stick of wood onto this fire, there's another similar formulation frequently seen in literature:
Many's the time I've seen her in my dreams.
And I'll also add a quote from Shakespeare (The Merchant of Venice):
Shylock: Signior Antonio, many a time and oft / In the Rialto you have
rated me / About my moneys and my
usances
The question this raises is, did Shakespeare recognize a difference between "many a time" and "oft"? Did it mean something more to him than how we would see it today, as interchangeable with "often"? Or was he gratuitously padding out a line to fit the meter?
Given your explanation, I'm not sure I would choose either word.
Some other options:
- inexperienced
- ingenuous
- unsophisticated
- naive
I think I would go with naive. It's often used as a synonym for "gullible", but its original sense seems perfect here.
Best Answer
Minnow has directed you to an excellent answer with an excellent diagram that illustrates what portions of the timeline the various English verb forms cover. There you'll find that the auxiliary has/have signals present perfect (completed action from an indeterminate time in the past all the way up to just about now), and the auxiliary had signals past perfect (completed action from an indeterminate time in the past prior to a fixed time in the past). Note how the tense of the verb affects the meaning of already.
Consider the present perfect with the verb "to leave": has already left:
Katy left at some time in the past, not specified. Already means that she departed up to this time, i.e., her departure preceded the present.
Now consider the past perfect: had already left:
Katy left at some time the past and her departure preceded a fixed past time, namely my arrival. Here already means that she departed up to that time, i.e., her departure preceded the fixed time in the past at which I arrived.