This is the 2495th most frequent Russian word.
прислала
"Прислала" means "she sent" in English.
The word "прислала" is in the past tense and shows that 'Mom' as the feminine subject sent something (a letter) to the speaker or someone else.
Мама прислала письмо.
Mom sent a letter.
Here "прислала" indicates a completed action in the past where the feminine subject 'She' sent a gift to 'me'.
Она прислала мне подарок на день рождения.
She sent me a present for my birthday.
In this sentence, "прислала" denotes an action by the feminine subject 'a friend' who sent photos, referring to the act of sending something to someone else.