mysqli_fetch_row() expects parameter 1 to be mysqli_result, boolean given

I'm making a project on Hotel Management using wamp server. In this I have to check the availability of a room and display it as available or not depending upon the Room Type. I have connected php to my mysql database. Now the problem is that I am accepting the room type from user and storing it in '$Room' and when I take "Room='$Room'"(where 'Room' is an attribute of the Table in my msql database) in my mysqli query it says that the value can't be of boolean (at line mysqli_fetch_row), but when I pass a value such as "Suites" it shows no error when I run it.

I have tried to do it without the mysqli_fetch_row and directly passed it in the if statement, but in that case it says that "Object of class mysqli_result could not be converted to int".

<?php
if(isset($_POST['room']))
{
    $Room=$_POST['Room'];

    $re1=mysqli_query($a,"select Available from availability where Room='$Room");
    $row1=mysqli_fetch_row($re1);
    $res1=$row1[0];

    if($res1<1)
    {
        echo "Unavailable";
    }
    else
    {
        echo "Available";
    }
}
?>

I want to be able to accept the value from the user and compare it in the if statement and if the value is less than 1 then it should say "Unvailable" else "Available".