Does the Anglicans believe in Trinity and in the same Saints than the Roman Catholics

I constantly hear about "Protestant" churches and I thought that only the Church of England and the Lutherans were protestants

Protestant is a rather ill-defined term, but most people use it to mean "anyone that isn't Catholic or Orthodox."

And, for the record, Anglicans consider themselves to be both Protestant and Catholic.

Anglicanism is different from Lutheranism. They both started very close to each other in time (within 12-15 years), but the motivation was very different. Lutheranism left the pope because of dogmatic differences, but Anglicanism split from the pope over mostly issued of money and power.

No, Protestants are all the Trinitarian churches which are neither Orthodox nor Catholic (including Sedevacantists, who are Catholic). Protestants differ in that they believe in the five "Silas":

Sola Scriptura - the Bible is a higher authority than the Church
Sola Gratia - salvation by grace alone rather than anything one does.
Solus Christus - no mediator other than Christ between God and us.
Sola Fide - justification by faith alone.
Soli Deo Gloria - glory to God alone.

That last one is relevant to your question about saints. To a Protestant, all saved people are "saints", but are not specially worthy. Only Christ is worthy.

All churches that are not under the pope are protestant.