Water resistant -absorb -last floor

I would like to have advices about my old home.It is old ,when it rains a lot because it is near the sea,the last floor (the floor that it is on the ground ,I dont know the exactly word ) ,it has water. Everytime it rains a lot,I am in the position to get out this water by hand. I haven’t the money to cover it now the floor so that it will not get water when it rains. What I can use or in low price that will stop the water or to absorb it somehow.