The Fed's job from Congress is to keep prices stable and employment high. It reads that as about 2% inflation, measured by the PCE price index. Its main tool is the short-term interest rate, set by the FOMC, and it can also expand or shrink its holdings of bonds.
Because that rate is the price of money for the whole economy, it matters for crypto too. Lower rates and more liquidity tend to help risky assets; higher rates tend to hurt them.