Liverpool Street Station is one of the main transport hubs of London. It's located next to Liverpool Street, the actual street, in the City of London. However, that street isn't the major road there. In fact both London Wall and the even larger Bishopsgate (A10) are much bigger. In fact one of the major exits from the main station is to Bishopsgate, and the other one is to Sun Street Passage. However that's the Rail section of the station. The Underground (Tube) section, while exiting into the overground and Overground sections, also exits unto a couple of streets - Liverpool Street being one of them. It's a very large station in a very dense part of the city.
The station serves both The City and Shoreditch since it's located on the boarder between the two. It also has intercity trains that go outside London, similar to Victoria, Euston, Kings Cross, Waterloo and Paddington stations.
It's surrounded by some colossal towers but the building itself is quite old and iconic. It's been renovated and expanded over the decades, but still has the old Liverpool street feel, much like Kings Cross or St. Pancras stations.
There are a few shops and restaurants inside the station building itself, including kiosks on the ground floor for quick takeaways, but proper restaurants and shops can be found immediately outside the station almost in any direction. Personally I'd head to Shoreditch for the best possible food. The food there is both better, and less expensive than that on the other side - The City.
Peace & Love,
Adé