This releases hydroxide ions when it is placed in aqueous solutions. Bases usually have some characteristics that will let you know if the solution is a base or not even before you try to test it out with a litmus paper.
First of all, the taste of the base is known to be bitter. This is different from acids that are usually sour. A lot of bases have the tendency to have a more slippery texture.
Some strong bases are not recommended to be mixed with acids because the reaction may be violent or extreme. A lot of bases also contain metal oxides so with this knowledge, it will be easier for you to know if the solution is a base or not.