Simple Player Movement - PlayerController.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerController : MonoBehaviour
{
    [SerializeField] private float _speed = 1;
    [SerializeField] private Rigidbody _rb;
    [SerializeField] private float _jumpForce = 300;

    void Update() {
        var vel = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical")) * _speed;
        vel.y = _rb.velocity.y;
        _rb.velocity = vel;

        if(Input.GetKeyDown(KeyCode.Space)) _rb.AddForce(Vector3.up * _jumpForce);
    }
}