It means they are a supplier of something, and have got the contract to supply whatever it is to those five businesses. You're right, "account" can mean many different things, and in this context it might have been clearer to say "we got the business to do [whatever it is they do] for these five places". But "account" is often used too. You see it especially in advertising, where an advertising agency might say "we won the British Airways account". This means that British Airways is now paying them to do all their advertising.

As polar vortex says, maybe for these kinds of business they could be the new caterers, or a laundry company (as you might imagine, hospitals, hotels and motels get through a LOT of laundry just in washing all that bed linen! Of course they have to change the sheets every time there's someone new in the bed).

Accounts consist of a Profit & Loss account and a Balance sheet.

The P&L shows how the profit/loss was made during the year. The balance sheet shows the state of the company on a certain date (all the assets balance with all the liabilities)

No, they may be catering suppliers, gardeners, laundry contractors etc. who have won the contracts to supply those businesses you mentioned. Maybe they are an accounting firm hired to do the financial books.

I don't think it's in the context of say a 'bank account' (or maybe it is?) but I was reading a paperback novel and i read the following....

"We got the Central Hospital account this year, as well as the mental institution and three new motels".

We 'got' the hospital account? does it mean.... they bought the hospital and therefore now 'own' the hospital and mental institution or something? help please.. what is meant by account, i don't understand!

Thanks!