What's the purpose of 给 here?

[snow nexus]

给 is used to indicate direction. You can omit it here it still means the same thing

It can't always be omitted though. You can only leave it out when the recipient of the object is obvious. Like for example
我送给你. If you remove 给 here, it might seem like you're sending the person instead of sending a gift to the person.

But in your sentence the object 东四 is already introduced so it's less ambiguous