The European Union has committed to the Paris Climate Agreement to be the first in the world to achieve complete climate neutrality by 2050 – this plan is called the Green Deal strategy. The first step to achieving this is to reduce greenhouse gas emissions by at least 55% by 2030 compared to 1990 levels. This effort is covered by the “Fit for 55” package of measures.
Ff55 is how the EU makes legislative proposals in different areas (like methane gas emissions and forestry) that affect various sectors (e.g., energy and accessibility). These proposals are voted on by the European Council (in one sentence, then link to the article about making these laws a reality).