Questions about how to efficiently use mysql pools with node.js

Reading the Documentation from mysql it offers the creation of pools, but it has a parameter called connectionLimit and mine doubt is on top of that! This limit that I will impose is in relation to:

So what's my code:

Controller:

exports.post = async (req, res, next) => {
const Email = req.body.Email;
const Passw = req.body.Password;
if(fluentValidation.validateEmail(Email) && fluentValidation.isValidLength(Passw)){
    try {        
      await sqlService.SignUpUser(Email,Passw,res,req);
    } catch (error) {
        console.log(error);
    }
}else{
    res.status(400).send({
        Error : "Email invalid"
    });
   }   
}

And I created a class called SQLService where it connects and I export methods to make queries.

const pool = sql.createPool ({
connectionLimit : 10,
host: '0.0.0.0',
user:'foo',
password : 'foo',
database : 'foo'
});


module.exports.SignUpUser = async (email,password,res,req) =>{
pool.getConnection(function(err,connection){
    if(err){
        console.log(err);
    }else{
        connection.query('select email from user where email = '${email}'', function (error, results, fields){
            if(results.length < 1){
                let date = dateT.getdate();
                let guid =  uuid();
                let etoken = uuid();
                connection.query('INSERT INTO e(e,e,e,e,e) VALUES ('${e}','${e}','${e}','${e}','${e}')', function (error, results, fields){
                    if(err){
                        console.log(err);
                    }else{
                        res.status(201).send();
                        emailService.send(req.body.Email,'Bem vindo ao e',url.buildUrl(req.headers.host,'/validate/'+ etoken));
                    }
                })
            }else{
                res.status(409).send();
            }
        });
        connection.release();
    }
  });
}

After I finish with the operation of this module that only has two queries connection.release(); , is this considered as two connections? I was a bit lost because I came from C # and using EntityFramework never had to worry about it! Thanks!