How do I make a realistic jump?

I am a beginner, I don’t really know how to code in c#. Can somebody help me making a realistic jump for my game? I tried everything but it just won’t work. I already have a moving script but really want to add a jump:

public class Movement : MonoBehaviour
	float speed = 10;
	public GameObject player;
    void Update ()
		// making vars of getting axis value
		float horizontal_movement = Input.GetAxis("Horizontal") * speed * Time.deltaTime;
		float vertical_movement = Input.GetAxis("Vertical") * speed * Time.deltaTime;
		float jump_movement = Input.GetAxis("Jump");
		// moving parts at X and Z Axis
		transform.Translate(horizontal_movement, 0, vertical_movement);
		player.transform.Translate(horizontal_movement, 0, vertical_movement);
		// moving parts at Y Axis
		//transform.Translate(0, jump_movement, 0);
		//player.transform.Translate(0, jump_movement, 0);

It really depends on the context, but a cheap and cheerful way is to maintain a height above some surface, and the rate of travel upward, then accelerate downwards constantly, limit height to be >= 0, and inject an impulse into the rate when the player presses jump:

const float jump_speed = 5;
float height=0;
float vspeed=0;

void FixedUpdate()
	float T = Time.fixedDeltaTime;
	const float gravity = -10;
	vspeed += T * gravity;
	if (player_pressed_jump)
		vspeed += jump_speed;
	height += T * vspeed;
	height = Mathf.Max(height, 0);

	//  lay this in where required, e.g.
	transform.position = new Vector3(0, height, 0);