Housing terminology

Here, we call it 2+1 unit (similar 2 BHK). It distinguishes by private units (known as condo) and govt apartments called HDB. Few areas, particularly at Marine Parade area HDB 2+1 units have one bathroom, where as most of places you will get two (one is attached with master bedroom). Every where condos (2+1) have two bath rooms. Similarly, 3+1, 4+1 units are available (in HDB n condo). Very rare 1+1 units are available, which are very old.

Thanks, Surya2k

Here are two more terms that I keep seeing, 'TOP' and 'rare'. What do they mean?

TOP stand for "Temporary Occupation Permit", which is given to a new building just after completion.
Rare means there are not many of that kind on the market (or at least the owner/agent claims - it's usually just marketing slang and can be ignored).

Thanks, Beppi. Think should stop looking at these websites and just hire an agent.

Agents cost quite a lot - and many of them do nothing but match the exact same websites' listings with what you said you want. In addition, many of them are either dishonest or put their own interest (for a high fee) over yours.
Look carefully and engage only an agent that comes with personal recommendations from somebody you know and trust (recommendations on the Web are usually fake). And negotiate the fee beforehand - try to get a flat fee that doesn't depend on the achieved rent!