Many special abilities and Force Powers require a character to Save against a listed number to avoid or reduce an adverse effect. Roll the d20. If the result of the roll equals or exceeds the listed number, the save succeeds. Saves are not optional, and characters cannot voluntarily choose to fail them.
If the rules text simply says “save” plus a number, the target of the effect makes the save. Sometimes the acting character makes a save instead, such as when using Lightsaber Block. In that case, the rules text specifies that the character producing the effect makes the save.