How many strings does a bass guitar have?
Most bass guitars have four strings.  Because the bass is designed for lower frequency than standard (usually six-string) guitars, the bass guitar strings are thicker and heavier than standard guitar strings.

Some basses are made with five or even six strings.  This allows the bassist to hit higher or lower notes than the standard bass guitar range, which can allow more creative freedom.  Four strings is still considered the standard for bass guitars, though.
Quantas cordas tem um baixo?
A maioria das guitarras de baixo tem quatro cordas. Como o baixo é projetado para uma frequência mais baixa do que as guitarras padrão (geralmente de seis cordas), as cordas de baixo são mais grossas e pesadas do que as cordas de guitarra padrão.