2% lignocaine is a solution of the local anaesthetic lignocaine (lidocaine) containing:

So:

It is used to numb an area before procedures, for nerve blocks, and sometimes epidural anesthesia. Lignocaine works by blocking sodium channels, stopping nerve pain signals.

It may be supplied plain or with adrenaline (epinephrine), which can prolong its effect and reduce bleeding. It must be dosed carefully because excessive systemic absorption or accidental intravascular injection can cause toxicity, including tingling around the mouth, tinnitus, seizures, low blood pressure, or dangerous heart-rhythm problems. The DailyMed product information confirms that 2% lidocaine injection is 20 mg/mL.