why is verb haber used here habra convocatorios

Hola Joanne

In this sentence from this dictation: 

Pero también habrá convocatorias para que nuevos fotógrafos puedan darse a conocer...

this means:

But there will also be calls for submissions so that new photographers can make themselves known..."

It's the use of "haber" in the future tense. 

Here's a useful lesson about haber in the futute tense.

Saludos

Inma