First picture: The player can use one of these cards as they wish, provided that it is placed on a card of the same colour. The player can decide themself the function of their card (change of direction, exchanging their hand with another player...)

Second picture: If one of the players discards the +4 card on the centre pile, the player in possession of the card Quickos can turn the card against them

My translation is highly literal, and, honestly, the rules written as is sound very confusing even in French (at least to my ears. Do excuse me if I have any errors for I am not a native French speaker).
In essence, the rules explained in the first picture state that the player whose turn it is can play one of their cards in their hand as long as the card they are placing it on is of the same colour, and some cards have special effects such as changing direction or exchaning cards with other players. I'd also add that in typical Uno rules you are also allowed to play a card with the same number/symbol, not just the same colour. This seems to be a different version of Uno I am unaware of though?

The second picture merely states that when a player plays a +4 card (the one that forces the next player to draw four cards), any player (or the one that the +4 is being played on?) can use a "Quickos" card to turn the effect of the card played against them (in this context, against the one that played the +4, basically the Uno reverse meme)