An Engpsh attributive clause is a clause that modifies a noun or pronoun and is introduced by a relative pronoun (such as "who," "that," or "which") or a relative adverb (such as "when" or "where").

For example:

The man who is wearing a red hat is my uncle. (The clause "who is wearing a red hat" modifies the noun "man" and is introduced by the relative pronoun "who.")
The book that I read last night was very interesting. (The clause "that I read last night" modifies the noun "book" and is introduced by the relative pronoun "that.")
The house where I grew up is on a quiet street. (The clause "where I grew up" modifies the noun "house" and is introduced by the relative adverb "where.")

To form an attributive clause, simply use a relative pronoun or adverb to introduce the clause, and then provide additional information about the noun or pronoun being modified.