Questions & Answers about Isto é suficiente.
A word-by-word breakdown is:
- Isto = this
- é = is
- suficiente = sufficient / enough
So the structure is very close to English: this is sufficient.
Both isto and isso can refer to this/that, but traditionally they are used a little differently:
- isto = something close to the speaker, or something not yet specified
- isso = something close to the listener, or something already mentioned
In modern Brazilian Portuguese, though, this distinction is often weakened in everyday speech, and isso is much more common than isto.
So while Isto é suficiente is correct, in real conversation many Brazilians would more naturally say:
- Isso é suficiente.
Yes, it is grammatical and perfectly understandable.
However, in everyday Brazilian Portuguese, isso is usually more common than isto, so:
- Isto é suficiente. = correct, slightly more careful or formal-sounding
- Isso é suficiente. = very common and natural in speech
So the sentence is fine, but it may sound a bit more textbook-like than the version with isso.