Short-term means roughly 0–2 years away. Medium-term means 2–5 years. Long-term means 5 or more years. The exact cutoffs matter less than what they tell you: how much time the money has to recover if something goes wrong.
Money you'll need soon has to stay stable and easy to access — the same idea as an emergency fund. There's no time to wait out a rough stretch. Money with a long runway can handle short-term ups and downs in exchange for better long-term growth — that's the whole idea behind the investing path ahead.
Keeping a 10-year goal entirely in a zero-growth account has a real cost too — inflation shrinks it over time, and it misses out on growth it had plenty of time to recover from if it dipped for a while. Keeping a 6-month goal in something risky puts you at real risk of a shortfall right when you need the money.
A short-term goal is a good fit for a UAE bank's fixed-term deposit — a set rate for a set period, in exchange for not touching the money early. It won't beat inflation over the long run, which is exactly why it's a short-term tool, not a long-term one.