Every time I open project, following warning is displayed. What does it mean?

Figure 4.3. Project is locked warning

Project has been exported and are going to be translated to other languages. Now is read-only because it is essential to preserve, that no change will be made to project during its copies are out for translation. If you want to know more, see “3.4.4. Export Project“. It is possible to unlock project, but be extremely careful (see “3.4.6. Unlock Project“)!