Something is firm if it is quite solid and doesn't move easily. Something is firmly attached if it doesn't wobble around or come loose. A sofa is firm if it is neither completely hard or soft. The sofa in the picture seems very firm.
Something is flammable if it is possible to set it on fire. Some things are more flammable than others, and a larger surface area tends to make things more flammable. For example, dry grass is highly flammable but large pieces of wood won't catch fire easily.
Something is flecked if it has small spots of another color through it. Many different kinds of stone are flecked, and the iris of many people's eyes are flecked.
Something is flexible if it can be easily bent into new shapes. Garden hoses are made of flexible plastic. The man in the picture is very flexible, and is a contortionist.
Something is foreign if it is from a different area or a different culture. Sometimes foreign things can look a bit out of place, like the duck in the picture.
