Yup for like 6 years. Is it short term?
I think you mean that you've held hundreds of thousands of dollars in short-term vehicles for 6 years so far. "Short-term dollars" means you have specific "lumpy" spending plans for those dollars in the near term. Examples include a wedding, an expensive/exotic vacation, business startup expenses, a child's university costs, a down payment on a home and/or renovations, an expensive professional development course (such as getting an MBA), or high likelihood professional care expenses for a frail parent or grandparent.
That's in contrast to "long-term dollars," meaning dollars that you would presumably spend in retirement and/or give away (to grandchildren for example) — that you have no near-term expectations to spend.
No long term plans at all. What vehicle is good to invest?
There are lots of threads about how best to invest long-term dollars, but the general practice is to pick a couple low cost index funds consisting of a global stock index fund (FWDA is one example), an investment grade corporate bond index fund (MBH notably), and possibly a Straits Times Index (STI) stock index fund (such as GAB). The ratio should be consistent with your expected time to retirement and risk tolerance. You would accumulate and hold these funds for decades, make periodic rebalancing adjustments especially as you approach retirement, and then spend them down over decades of retirement. "Long-term" means long-term.
So if sa is closed and all money frs sa, all into ra, the money in ra is not fixed? Still can take out?
Correct. Since you've evidently used OA dollars for housing, you evidently already have a property charge in place. If your home is a freehold, or it's a leasehold that'll last at least until you're 95, it qualifies to allow you to make a large lump sum RA withdrawal from age 55+.
Just because you
can make a lump sum withdrawal from RA doesn't mean you should or must. Reducing your lifetime retirement income and foregoing 4.0+% RA interest are usually unattractive outcomes.
I have the idea that the money goes In can't be taken out anymore after 55. Can pledge hdb at let's say 60, and take out some to use, over a period of time?
You don't even need to pledge a home if you already have a qualified property charge in place. Yes, you could withdraw a substantial amount from RA in that scenario. (Exactly how much will depend on your age 55 Basic Retirement Sum and whether you've made any prior cash top ups to your SA or RA to reach the Full Retirement Sum.)