my character keeps jumping infinitely, i want it to be a single jump, please can anyone help

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class PlayerCtrl : MonoBehaviour
6. {
7.     public bool canjump = false;
8.     public Animator animtor;
9.     public float waittime = 0.5f;
10.     private float jumpvel = 10;
11. public int MovementSpeed;
12. public Rigidbody2D rb;
13. float mx;
14.  
15. private void Update()
16. {
17.      if (Input.GetKeyDown(KeyCode.P))
18.      {
19.  
20.      }
21.      if (Input.GetKeyDown(KeyCode.Space))
22.      {
23.          if (canjump == true)
24.          {
25.          animtor.SetBool("IsSpacePressed", true);
26.          rb.velocity = Vector2.up * jumpvel;
27.          }
28.      }
29.      mx = Input.GetAxisRaw("Horizontal");
30. }
31. private void FixedUpdate()
32. {
33.      Vector2 movement = new Vector2(mx * MovementSpeed, rb.velocity.y);
34.  
35.      rb.velocity = movement;
36. }
37. private void OnTriggerEnter2D(Collider2D col)
38. {
39. if (col.gameObject.CompareTag("Map"))
40. {
41.     if (rb.velocity.y < 0)
42.     {
43. canjump = true;
44.     animtor.SetBool("IsSpacePressed", false);
45.     }
46.     else
47.     {
48.         canjump = false;
49.     }
50. }
51. }
52. }
53.  

 

You don't set the bool to false, also, this is not the best idea, as you can hit a wall and be able to jump and it's god awful to test if the player ran off the edge without jumping.
Instead I'd suggest creating a small trigger at the foot of the player and have that check if it's being collided with the ground.