lie(present), lay(past tense), lain (past participle), Lying(present continuous ): these verb forms are intransitive verbs; they do not require an object.

Lay(present), Laid (past tense), Laid(past participle), Laying (present continuous): these verb forms are transitive verbs; they require an object to complete its meaning.

He(subject) laid(past tense) the picture(object) on the table (prepositional phrase).

Lay means to put down gently or place in a position for use.