هي لم يكن عليها فعل هذا.

English Translation

She shouldn’t have done that.

The Arabic sentence “هي لم يكن عليها فعل هذا” is written as:

هِيَ لَمْ يَكُنْ عَلَيْهَا فِعْلُ هَذا

Word-by-word breakdown:
هِيَ (hiyā): She (third-person feminine singular pronoun).
لَمْ (lam): A negation particle used for the past tense, meaning “not” or “did not.”
يَكُنْ (yakun): To be (verb in the past tense, masculine singular form, here used in a negative context).
عَلَيْهَا (ʿalayhā): On her (preposition “on” + object pronoun “her”).
فِعْلُ (fiʿlu): Action or deed (noun in nominative case, meaning “the action”).
هَذا (hādhā): This (demonstrative pronoun, masculine singular).
Complete sentence translation:
“She should not have done this.”

Grammar and Morphology Explanation:
هِيَ: A pronoun that serves as the subject of the sentence, referring to a female.
لَمْ: A particle that negates the verb that follows it in the past tense. It indicates that the action did not take place.
يَكُنْ: A form of the verb “to be,” here used in the past tense. Even though it is masculine, it is used with the feminine subject because of the negation particle لَمْ.
عَلَيْهَا: This prepositional phrase indicates that the action in question was expected of “her.”
فِعْلُ: This noun indicates the action that is being referred to in the sentence.
هَذا: A demonstrative pronoun indicating “this,” pointing to the specific action mentioned.
The sentence expresses a judgment or opinion about an action that the subject (she) should not have performed.