Learn German: Ich suche die Post und eine Bank. - I am looking for the post office and a bank.

In English, we say we are looking 'for' something. In German, the verb suchen already means 'to look for' or 'to seek'. You just follow it directly with the thing you are trying to find, so no extra prepositions are needed!

Since we are practicing the accusative case, why don't die Post and eine Bank change their endings?

Both Post and Bank are feminine words. In the accusative case (which we use for direct objects, like the things you are looking for), feminine articles like die and eine stay exactly the same as they are in the basic dictionary form. Only masculine words change their articles, like changing der to den or ein to einen.

Why are the words Post and Bank capitalized?

In German, every single noun (a person, place, thing, or idea) is capitalized regardless of where it appears in the sentence. Since a post office (Post) and a bank (Bank) are places or things, they must always start with a capital letter.

Does Bank mean a money bank or a park bench?

It can actually mean both! Just like in English, context is key. Here, paired with the post office, it almost certainly means a financial bank. If you were walking in a park, it would mean a bench.