I start wondering if the country is important when choosing a journal to submit my paper? If my university and I are in country A, can I still submit an article to journal from country B? Or only "International " journals available for me?
For most journals, this will not be important.
For example, the British Ecological Society and Ecological Society of America both publish journals that are open to ecologists globally.
Sometimes, there are regional journals that only focus on specific regions.
Conversely, some journals like the Canadian Field Naturalist historically have had geographic specific missions. For example, CFN describes (described? I'm having trouble finding this quote on their current homepage) itself as
A peer-reviewed scientific journal publishing ecology, behaviour, taxonomy, conservation, and other topics relevant to Canadian natural history.
Hence, a paper on Australian species would not be relevant unless the paper tied back to Canada or Canadian species somehow.
More broadly, you can find this out by reading the "about", "author's instruction", or similar section of the journal as well as reading recent articles (or at least skimming titles and abstracts).
Edit: Based upon a comment from Buffy, there are also journals that limit authors based upon their affiliation.
For example, The Texas Journal of Science is limited to work done in Texas or nearby areas OR done by Texas scientists anywhere (bold added by me):
The geographic scope of manuscripts published in the Journal are generally limited to work conducted by authors while at Texas institutions or to work conducted in Texas or adjacent areas (surrounding states and Mexico) that has some direct relevance to Texas natural history (regardless of author’s institutional location).