Depends on the structure of these blocks. If it is a parent - child relationship, then it can be solved by css, if it’s an unrelated block, you need to use javascript.
$(document).ready(function() {
$(".triggerclassname").hover(function() {
$(".targetclassname").css("background-color", "yellow");
}, function() {
/* when the mouse is out return it back to normal */
$(".targetclassname").css("background-color", "transparent");
});
});