Learn Russian: Кто-то подъехал к парковке магазина. - Someone drove up to the store's parking lot.

The prefix под- ends in a consonant. When attaching it to a verb root that starts with е, ё, ю, or я, Russian requires a hard sign (ъ). This prevents the consonant from softening and keeps the y-sound of the vowel clear, making it easier to pronounce the two parts separately.

Why do we use the preposition к here?

Verbs of motion with the prefix под- mean approaching or getting close to a target. This prefix is strongly paired with the preposition к (meaning towards) plus the Dative case. Together, подъехал к парковке shows the action of driving right up to the boundary of the parking lot.

How do we know this person arrived in a vehicle rather than on foot?

The verb подъехать is based on the root ехать, which specifically means to travel by transport. If someone walked up to the parking lot, the sentence would use подошёл, which is based on идти (to go on foot).

Why use Кто-то instead of Кто-нибудь for someone?

The suffix -то is used when the someone is a specific person whose identity is just unknown to the speaker, which is common in past-tense factual statements like this one. The suffix -нибудь is for hypothetical situations, like asking if anyone drove up or telling someone to go drive up.