Hi,
I'm not sure I understand your question here. What "tabs" are you talking about? Tabs in the DSpace User Interface? Or do you mean the title of your browser's tab? If it's the title of your Browser's tab, that text is controlled in your Internationalization file. For example, it's here in the default "en.json5" file:
https://github.com/DSpace/dspace-angular/blob/main/src/assets/i18n/en.json5#L3103-L3105
Almost all text in DSpace is in those "i18n/*.json5" files. So, if that's not what you are looking for, chances are the text you are talking about is found in that file.
If I've misunderstood the question, let us know on this list by providing us with more details around your question.
Tim