test.js

router.get('/brand/:smabrand', function(req, res) {
    const smaquery = req.query;
    // [..]
        
    let getProductCount=async function(smaquery){
          let count= await Products.countDocuments(smaquery);

          console.log(count)
          if (count === 0) {
            return res.send("Brand not found!");
          }
    }
})