I want the player to be able to jump only once he collects the ability to jump in 3d and I don't know how to, help pls.

Questions & Answers
1

(Like in Hollow Knight that the player need to collect the abillity to dash or double jump)

2

In your movement script:

bool canJump = false;
void Update()
{
canJump = PlayerPrefs.GetInt("hasJumpAbility") == 1;
}
void Jump()
{
 if(!canJump){ return; }
 else
 {
  //do the jump code here
 }
}

in some player script (even movement is you want)

OnTiggerEnter(Collider other)
{
if(other.CompareTag("Item"))
{
if(other.gameObject.name == "JumpAbility")
{
PlayerPrefs.SetInt("hasJumpAbility",1); 
PlayerPrefs.Save();
}
}