How do I pass parameter by onclick?

Try something like this:

editBtn = '<a type="button" onclick="javascript:Devolver('
        + "'XXX'"
        + ')"><span class="btn btn-danger">Devolver</span></a>';
editBtn = editBtn.replace('XXX', row.PlacaDoVeiculo);
return editBtn;

Note that you had also forgotten the > before the <span that closes the <a tag.

And next time, please put the code as text in your question. Everyone on this site hates to see code inside images.