"At risk of becoming endangered" refers to a species whose population is declining and faces threats that could lead to its status changing from vulnerable to endangered. Factors contributing to this risk often include habitat loss, climate change, pollution, overexploitation, invasive species, and disease.
To conserve such species, efforts are typically made through habitat preservation, legal protections, breeding programs, and public awareness campaigns. Conservation organizations may monitor populations and work to mitigate the threats they face in order to help stabilize and recover numbers.
If you have a specific species or context in mind, I would be happy to provide more detailed information!