ETF stands for exchange traded fund: a fund whose units are bought and sold on the market throughout the trading day at the prevailing price, rather than once a day like a traditional fund.
Most ETFs are index funds, but the two are not synonyms: there are actively managed, leveraged, sector and thematic ETFs, and some are expensive, concentrated products wearing a popular label. That something is an ETF tells you nothing about whether it is a good idea; what matters is what it tracks, what it costs and how it tracks it.
Domicile and structure also affect the tax you pay on dividends, and that depends on where you live. It is one of the few decisions here where local tax treatment matters more than the product, and it is worth checking with a registered professional.