Putoavia is the partitive plural of putoava, the present participle of the verb pudota, which means ”to drop” or ”to fall (down/off)”. Putoavia in our example functions like an adjective and means ”falling.”
To make the present participle, you take the third persoformn plural of the verb, remove the -vat/-vät, and add -va/-vä.
The participle should be in the same form as the word it is connected to. In this case, it modifies esineitä, the partitive plural of esine, which means ”object.” Putoavia esineitä means ”falling objects.”
Varo is the imperative of varoa, and here means ”look out (for).” Our whole sentence, ”Varo putoavia esineitä” means ”Look out for falling objects.”