Acknowledgement
Acknowledgement: a document that acknowledges something.
The base: Acknowledge
An example of the first meaning is, "I acknowledge that the sky is blue, but why is that?"
An example for the second meaning is, "Please acknowledge me by allowing me to speak!"
The suffix: -ment
In general, the suffix ment, can change an adjective to a noun, such as joy from joyful, but it can also change verbs to nouns, in this case acknowledgement from acknowledge.
The whole thing: acknowledgement
Acknowledgement is the noun form of acknowledge. to acknowledge is to accept, an acknowledgement is a written document acknowledging something or someone.
To acknowledge is a verb, but adding the suffix -ment makes it a noun. Acknowledgement. If it were to be taken literally it would be "the thing that acknowledges".
The picture below is of an acknowledgement.
An acknowledgement of thanks would be used if someone did something important and they wanted to thank people who they think helped them along the way.