what is $(`#${chatBoxId}`) in the code is accesing? (javascript)

Question

constructor(chatBoxId, userEmail)
    {
        this.chatBox = $(`#${chatBoxId}`);
        this.userEmail = userEmail;
        this.socket = io.connect(process.env.CODEIAL_CHAT_SERVER);

        if (this.userEmail)
        {
            this.connectionHandler();
        }

I am using this code for socket.io in the code but am not understanding, what is $(#${chatBoxId}) selector used for?