The word said is the past tense of the verb "say," but it can also be used as an adjective to refer to something that has been previously introduced.
Although said is most commonly used as the past tense of the verb say, its use as an adjective comes mainly in legal and business writing. In that vein, the word offers a reference to something that was mentioned earlier. The judge may tell you that if you can't provide said evidence, your case will be dismissed. That evidence was mentioned before. If you don't know what the said example is, you must not have been paying attention.