Like PCR, but does not require thermal cycling. Thus the "isothermal" in the name: iso means same, so "same temperature".
Not needing the thermo cycling means that the equipment needed is much smaller and cheaper it seems.
Trade-offs question: biology.stackexchange.com/questions/92172/what-are-the-trade-offs-between-polymerase-chain-reaction-pcr-vs-loop-mediated