Learn Spanish (Latin America): Alguien me prestó esta linterna ayer. - Someone lent me this flashlight yesterday.

We only use the 'personal a' when a person is the object of the sentence (the one receiving the action). In this sentence, alguien is the subject (the one doing the lending). If the sentence were 'I saw someone', you would say Vi a alguien because 'someone' would be the object receiving the action of being seen.

Does alguien always use a singular verb?

Yes! The indefinite pronoun alguien (someone/somebody) always takes the third-person singular form of the verb, just like él or ella. That is why we use prestó here instead of a plural form, even if the 'someone' could hypothetically be more than one person.

Why do we use esta instead of esto or está?

Esta (without an accent) is the feminine singular word for 'this', perfectly matching the feminine noun linterna. Esto is the gender-neutral 'this', which is only used for unknown objects or general ideas, never right next to a noun. Finally, está (with an accent) is a completely different word: it is the verb 'is' from estar.

Why is me placed before prestó? Could I attach it to the end?