Hi Dawid,
Greetings from Syncfusion support.
By default, our calendar component will display the full month name in the header. Please refer to the sample below,
So, can you please provide below details that help us to proceed further.
1. Do you need a full month name on the calendar?
2. Whether the shared screenshot is the Syncfusion calendar?
3. Have you used the culture in your application? If so, please include the culture info.
4. For a clear understanding, elaborate more on your query.
Regards,
Sevvandhi N