estimessin

form-of imperfect plural subjunctive third-person

（活用形）動詞『estimar』の第三者複数形過去未完了仮定法形

English Meaning

third-person plural imperfect subjunctive form of estimar

Si estimessin la natura, no tirarien tanta brossa a la platja.

もし彼らが自然を愛していたら、海辺にそんなにゴミを捨てないだろう。

If they loved nature, they wouldn't throw so much trash on the beach.