<select id="division" multiple="multiple" title="Equipos seleccionados" style="width:143px;height:125px;overflow:scroll;">
<option value="1" title="Bundesliga">Bundesliga</option>
</select>

_spBodyOnLoadFunctionNames.push("hideFields");

function hideFields() {
    var control = findcontrol("equipo");
    control.parentNode.parentNode.parentNode.style.display = "none";
}

function showFields() {
    var control = findcontrol("equipo");
    control.parentNode.parentNode.parentNode.style.display = "block";
}

function findcontrol(field) {
    var arr = document.getElementById(field);
    return arr;
}

var values = document.getElementById('division').val();;
if (values != null || values != ''){
    showFields();
}