。
Everything's going smoothly.
Literal
All-things smooth [adverbial-に] is-going.
順調に ('smoothly, without a hitch') is a na-adjective in adverbial form — 順調 'smooth' + に = 'smoothly.' 行っている is the ~ている of 行く ('go'), here marking the ongoing state of 'proceeding.' A handy phrase for reassuring someone that a project, plan, or recovery is on track.