Yes, you can change House size into "persons". with help Language Manager in Joomla real estate extension.
1. Go to admin area Components -> Real Estate Manager -> Language Manager.
2. In the drop down list Select Language choose needed language.
3. Then search the word or word combination which you want to change in the field Search by value constant, click on it and rename Value Constant
About icon for "persons" - we use favicons for that. You can add your in code, you need edit file default.php
and edit that code
<i class="fa fa-expand"></i>
<span class="col_text_1"><?php echo _REALESTATE_MANAGER_LABEL_HOUSE_SIZE; ?>:</span>
Before make any change make a copy of file.
We advice you choose PRO version, it has more opportunities.