The adjustment of suspensions has a great influence on the behaviour of the car on the circuit. According with it, the car can understeer, oversteer or be neutral.
In simple terms, if the suspension is more flexible, the car will move quickly in turns with more adherence, but it will react less quickly to the requests of the pilot. With a hard suspension, adherence will be less, but the car will be sharper, faster to react, which is ideal for a circuit with a lot of hard bends.
The suspensions must be soft enough to absorb the bumps on the track and hard enough to support the heavy load generated by downforce.