We've a vague equivalent of a Wound-Vitality system, which makes it more complicated; but the short form is that for a "long rest" you get back 1/10 of your full h.p. value, rounding ANY fractions up (so someone whose full h.p. is 20 gets back 2, someone whose full is 21 gets back 3). It's slower if you're into Wound points. We use the fractional version because otherwise is takes high-level warrior types just too long to recover.
That said, if a party in the field does nothing but rest for a day they can benefit from two of these long rests during that day; if in a safe place in town it becomes 3 per day. But they just help hit points; everything else only refreshes overnight.
We don't have short rests like 5e does, but immediately a battle's over (or damage has been taken in other means e.g. you fell in a pit trap) you can take a breather for a couple of minutes* and recover d3 h.p. provided you're not in Wound points. Must be done before any other type of curing, or else the opportunity is lost; and it can't fix damage not just taken.
* - the assumption here is during this time you're tending your scrapes, getting a quick drink, stretching out, catching your breath, and so forth.