Namespace: unity doesnt recognize"NavigationSurface"

“Help me. I’m don’t know how to write a single sentence or how to ask a question.”

Namespace: unity doesnt recognize"NavigationSurface"

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Unity.AI.Navigation; //doest recognize
using UnityEngine.AI; //doest recognize

public class NaviMeshManager : MonoBehaviour
{
    public NavigationSurface[] surfaces;
    public void UpdateNavigationMesh()
    {
        surfaces = FindObjectsOfType<NavigationSurface>();

        // Update the NavigationSurface
        for (int i = 0; i < surfaces.Length; i++)
        {
            surfaces[i].BuildNavMesh();
        }

        Debug.Log("updating ALL nav mesh");
    }
}

Did you install the AI navigation package?, from the package manager > unity registry and install AI navigation, then try.