Refactoring code for S.O.L.I.D principles

I want to learn SOLID but its really hard for me. I don' t know where to start. After watching materials and still not being able to refactor my own code I decided to ask here. How would you refactor such a code. Seeing an example of someone more experienced would mean a lot to me.

Thanks in advice :)

 public class Player : MonoBehaviour
 {
     [SerializeField] [Range(0f, 1000f)] float movementSpeed = 654;
     [SerializeField] [Range(0f, 60f)] float playerControlledJumpForce = 30.3f;
     [SerializeField] [Range(1f, 40f)] float timesJumpForceAtFrameIsSmaller = 31.25f;
     [SerializeField] [Range(0f, 60f)] float fromEnemyJumpForce = 15.9f;
     [SerializeField] int maxJumps = 1;
     [SerializeField] [Range (0f, 1f)] float minTimeBetweenJumps = 0.005f;
     float playerAtFrameControlledJumpForce;
 
     //private IJump; 
     
 
     private int jumpsLeft;
     private bool isJumping = false;
 
 
     float lastJumpTime = 0;
 
     new Rigidbody rigidbody;
 
     SessionManager sessionManager;
     
 
 
     // Start is called before the first frame update
     void Start()
     {
         sessionManager = FindObjectOfType<SessionManager>();
 
         rigidbody = GetComponent<Rigidbody>();
 
         jumpsLeft = maxJumps;
 
         playerAtFrameControlledJumpForce = playerControlledJumpForce / timesJumpForceAtFrameIsSmaller;
     }
 
     // Update is called once per frame
     void Update()
     {     
        PlayerControlledJump();
 
        HorizontalMovement();
     }
 
     private void Jump(float jumpForce)
     {      
         Vector3 jumpVelocityToAdd = new Vector3(rigidbody.velocity.x, jumpForce,0);
         rigidbody.velocity += jumpVelocityToAdd;
     }
 
     private void PlayerControlledJump()
     {      
         if (Input.GetKeyDown(KeyCode.Space)
             && jumpsLeft > 0)
         {
             #region
             if (!(Time.time - lastJumpTime >= minTimeBetweenJumps))
             {
                 return;
             }
             lastJumpTime = Time.time;
             #endregion
 
             jumpsLeft--;
 
             isJumping = true;
 
             Jump(playerControlledJumpForce);
         }
         if (Input.GetKey(KeyCode.Space) && isJumping)
         {
             Jump(playerAtFrameControlledJumpForce);
         }
         if (Input.GetKeyUp(KeyCode.Space) || rigidbody.velocity.y < 0f)
         {
             isJumping = false;
         }
     }
     private void HorizontalMovement() // TODO, take it out to separete class for SOLID principles
     {
         float movementScalar = movementSpeed * Time.deltaTime;
         
         rigidbody.velocity = new Vector3(Input.GetAxisRaw("Horizontal") * movementScalar, rigidbody.velocity.y, rigidbody.velocity.z);
     }
 
     private void OnCollisionEnter(Collision collision)
     {
 
         if (collision.gameObject.tag == "Enemy")
         {
             GameOver();
           
         }
 
         if(collision.gameObject.tag == "DeathCollider")
         {
             Jump(fromEnemyJumpForce);
             
         }
 
 
         if (collision.gameObject.layer == 8)
         {
             jumpsLeft = maxJumps;
         }
         else if(collision.gameObject.layer == 9)//Zero Level layer
         {
             GameOver();
             
         }
     }
     private void OnCollisionExit(Collision collision)
     {
         if(collision.gameObject.layer == 8) // Ground layer
         {
             jumpsLeft = 0;
         }
         
     }
     private void GameOver()
     {
         Debug.Log("GAME OVER");
         sessionManager.ReloadCurrentScene();
         Destroy(gameObject);
         //TODO proceed game over
     }
 }