Inflation is a general rise in prices. Seen from the other side, it is your money losing purchasing power.
Central banks such as the ECB target about 2% inflation a year over the medium term. That sounds small, but it compounds: at 2% a year, prices double and money buys half as much in about 35 years.
Bitcoin's answer
Bitcoin's supply schedule is fixed in its code and capped at just under 21 million coins. New issuance falls at each halving. No one can decide to create more to fund spending. Its price still swings a lot in the short term, so it is not a stable unit of account today, but its supply rules are predictable and public.