Learn Romanian: Unde este aparatul? L-am verificat ieri. - Where is the device? I checked it yesterday.

In Romanian, neuter nouns behave exactly like masculine nouns in the singular, and like feminine nouns in the plural. Since aparatul is singular ("the device"), it takes the masculine singular pronoun îl, which shortens to l- before a vowel.

What exactly is happening with the hyphen in "l-am"?

L-am combines the pronoun îl (meaning "it" or "him") with am (the helper verb "I have"). To make it easier to say quickly, the î is dropped and the pronoun attaches directly to the helper verb with a hyphen.

If the sentence were about plural devices (aparatele), how would "L-am verificat" change?

Because neuter nouns act feminine in the plural, you would use the feminine/neuter plural pronoun le. The phrase would become Le-am verificat ("I checked them").

Does the verb "verificat" change its ending to match the object we are talking about?

Not here! In the past tense, a past participle like verificat doesn't change its ending when you use the masculine pronoun l- or the plural pronouns i- or le-. It stays in its default dictionary form.