https://en.wikipedia.org/wiki/Magnetohydrodynamic_generator is the gist of it. If you have enough conductive plasma then just moving it through a magnetic field generates a current. Applied to fusion power, you heat the plasma through the fusion reaction then divert part of the plasma through the MHD generator.

Tbh, I very much doubt that this is a realistic path in the coming decade (but would love to be proven wrong). AFAIK no experimental reactor has yet generated any net electrical power at all, let alone with any big (ie dozens to hundreds of) MW MHD generators. Getting even one of these aspects working would be a major advance, let alone doing both at once.