While it's technically just the opposite of "non-flammable", it often carries the implication of danger and risk of fire. This is because the word "inflammable" is often used in contexts related to warning about the potential for something to catch fire easily.
For example, you'd likely see a warning label on a container of gasoline saying "Flammable" or "Inflammable", rather than "Non-flammable".
To avoid any confusion, it's generally recommended to use the word "flammable" instead of "inflammable" when you want to communicate the potential for fire.