These two properties work in a similar fashion as the overflow property and accept the same values. The overflow-x parameter works only on the x or left-to-right axis. The overflow-y works on the y or top-to-bottom axis.

HTML

<div id="div-x">
    If this div is too small to display its contents, 
    the content to the left and right will be clipped.
</div>

<div id="div-y">
    If this div is too small to display its contents, 
    the content to the top and bottom will be clipped.
</div>

CSS

div {
    width: 200px;
    height: 200px;
}

#div-x {
    overflow-x: hidden;
}

#div-y {
    overflow-y: hidden;
}