Etno-relihiyoso is Tagalog for Ethno-religious.
Ethno-religious groups are groups of people that are defined both by a unique spiritual belief as well as being considered a unique ethnic group. The Jews are the most commonly known example, but there are also the Druze and the Yazidi among others.
Ethno-religious groups have certain elements that are common to all ethnicities, such as a common language, a common ancestry, particular customs of association, and a view of common historic nation-hood. It also has certain elements that other religions share such as a belief in divine beings and a God, specific divine mandates, houses of worship, and holy scriptures.
Some people like to say that an ethno-religious group functions like a nationality. Ethno-religious groups, unlike other common religions, prevent a person from converting out. This is because the ethnic component of group ties a person in regardless of what they believe. This is as opposed to a pure religion, like Christianity, where failure to believe in the Christ makes a person a non-Christian. However, a person can gain a nationality through a difficult process of citizenship-acquisition. This is because the religious component of the ethno-religious group accepts conversion. This is as opposed to a pure ethnicity, like Italian. A person cannot convert to Italian as much as he may like spaghetti and Pizza.