Low stakes means betting small amounts per spin, often anywhere from a few pence to well under a pound. "Penny slots" is the informal name, though modern games rarely allow a single penny per spin across all lines.
Small stakes reduce the cost of play per spin, not the percentage. The house edge is the same at any stake, so expected loss is still total staked × (1 − RTP). Because each spin costs little, though, the same budget lasts longer. Illustrative example: £20 at 10p a spin is 200 spins of stake, against 20 spins at £1.
Low stakes do not make a game safer in itself. Speed of play matters as well: on GB online slots the minimum 2.5-second game cycle caps play at 1,440 spins an hour, which at 20p a spin is still £288 staked.