Chinese and Spanish-origin surnames are the most common in the Philippines
Because of Chinese immigration starting from the pre-discovery of the Philippines (for trading goods and doing business here) up to present, there have been a large population of Filipino-Chinese. Hence, we have chinese family names like "Chua", "Dy", "Sy", "Lee", "Lim" and "Tan" to name a few.
As for the Spanish surnames, there was a time when we were still a colony of Spain, governor-general Claveria issued a decree that all Filipinos must adopt a surname (we only have first names back then). This was done to ease their census making in the country. (Yey, i still remember my history class!)
They distributed a handbook containing Spanish surnames where families can choose their preferred surname. Some are "Santos", "Reyes", "Lopez", "Martinez", "Morales" , "Castillo", "Cruz"
There are those who haven't chosen from the list, and instead used a Filipino surname like yours. Mabaet (Mabait) is a tagalog word for "good" or "kind".
I have a Spanish surname.