The development files are the include files needed to compile C programs, the PKG-CONFIG .pc files and the static libraries.
|-- include
| `-- libgda-5.0
| [... except the libgdaui/ directory ...]
`-- lib
|-- libgda-5.0
|-- libgda-5.0.a
|-- libgda-5.0.la
|-- libgda-report-5.0.a
|-- libgda-report-5.0.la
|-- libgda-xslt-5.0.a
|-- libgda-xslt-5.0.la
`-- pkgconfig
|-- libgda-5.0.pc
|-- libgda-report-5.0.pc
`-- libgda-xslt-5.0.pc