Is replacing a vague pronoun

No, the Word 'replacing' is NOT a pronoun.

The Word 'replacing' is the present participle, present tense of the verb to 'replace'. The present participle of the verb also functions as an adjective and a gerund (a verbal noun).

A pronoun is a Word that takes the place of a noun in a sentence.

Example: Replacing a tire is new for me. Ittook me some time to do.

• The pronoun 'it' takes the place of the noun 'replacing' in the second sentence.