Support and Resistance is a technical analysis concept / strategy used by traders to refer to the price levels on the charts for a security.
On a chart, resistance is the area around the highest point the price of a security reaches before it is pulled back i.e prices start going down. Resistance levels indicate that there are / will be surplus of sellers for that particular security.
On a chart for a security, support is the lowest point reached before it continues to go up again.
Support levels indicate that there are / will be surplus of buyers for the traded asset.