Vita est brevis
life is short
ars longa
art long
(here and in the rest of the phrase, "est," 3rd singular person active form of the verb to be, is carried from the previous part to the rest so to mean "art IS long")
vicis volatilis
change swift, change is swift
experiment proditus ratio difficilis
(here "experiment" should probably read "experimentUM" to make any sense, since "experiment" is not declined.) If so,:
"experience having being put forth consideration is difficult"
Hope this helps.