Vielleicht: maybe, perhaps, possibly, probably, presumedly. Or, to say it the old-fashioned, archaic way: mayhap, belike. Other German words like „mutmaßlich“ are quite similar to „vielleicht“ but potentially a little less tentative.
„Vielleicht“ is definitely maybe the most interesting among them. Cut it in half, and you’ll discover „viel“ and „leicht“. „Much, very“ and „easy“. This literal sense underlines the open possibility of an easy change of mind or heart.