WCAG COMPITABILITY

I am trying to make my webstite compitable with wcag 2.0. But wcag chackers shows this problem: select element missing an associated label.  Please let me know about a way to pass this warning.

Code of certain line is:

1. <li><select id=”pa_size” class=” hide woo-variation-raw-select woo-variation-raw-type-button” style=”display:none” name=”attribute_pa_size” data-attribute_name=”attribute_pa_size” data-show_option_none=”yes”><option value=””>Κάντε μία επιλογή</option><option value=”36″ >36</option><option value=”37″ >37</option><option value=”38″ >38</option><option value=”39″ >39</option><option value=”40″ >40</option></select><ul role=”radiogroup” aria-label=”ΜΕΓΕΘΟΣ” class=”variable-items-wrapper button-variable-wrapper wvs-archive-variable-wrapper wvs-catalog-variable-wrapper reselect-clear” data-attribute_name=”attribute_pa_size” data-attribute_values=”[&quot;36&quot;,&quot;37&quot;,&quot;38&quot;,&quot;39&quot;,&quot;40&quot;]”><li data-url=”https://www.littlefeet.gr/product/pretty-soft-pedila-1511/?attribute_pa_size=36″ aria-checked=”false” data-wvstooltip=”36″ class=”variable-item button-variable-item button-variable-item-36 ” data-title=”36″ title=”36″ data-value=”36″ role=”radio” tabindex=”0″><div class=”variable-item-contents”><span class=”variable-item-span variable-item-span-button”>36</span></div></li><li data-url=”https://www.littlefeet.gr/product/pretty-soft-pedila-1511/?attribute_pa_size=37″ aria-checked=”false” data-wvstooltip=”37″ class=”variable-item button-variable-item button-variable-item-37 ” data-title=”37″ title=”37″ data-value=”37″ role=”radio” tabindex=”0″><div class=”variable-item-contents”><span class=”variable-item-span variable-item-span-button”>37</span></div></li><li data-url=”https://www.littlefeet.gr/product/pretty-soft-pedila-1511/?attribute_pa_size=38″ aria-checked=”false” data-wvstooltip=”38″ class=”variable-item button-variable-item button-variable-item-38 ” data-title=”38″ title=”38″ data-value=”38″ role=”radio” tabindex=”0″><div class=”variable-item-contents”><span class=”variable-item-span variable-item-span-button”>38</span></div></li><li data-url=”https://www.littlefeet.gr/product/pretty-soft-pedila-1511/?attribute_pa_size=39″ aria-checked=”false” data-wvstooltip=”39″ class=”variable-item button-variable-item button-variable-item-39 ” data-title=”39″ title=”39″ data-value=”39″ role=”radio” tabindex=”0″><div class=”variable-item-contents”><span class=”variable-item-span variable-item-span-button”>39</span></div></li><li data-url=”https://www.littlefeet.gr/product/pretty-soft-pedila-1511/?attribute_pa_size=40″ aria-checked=”false” data-wvstooltip=”40″ class=”variable-item button-variable-item button-variable-item-40 ” data-title=”40″ title=”40″ data-value=”40″ role=”radio” tabindex=”0″><div class=”variable-item-contents”><span class=”variable-item-span variable-item-span-button”>40</span></div></li></ul></li> </ul>