Let's say that in clockwise order around the table you have Players A, B, C and D, and the play direction is clockwise at the moment. Player A plays a Skip card. Player B's turn is skipped; he does absolutely nothing (except catch Player A for not saying "Uno" if applicable). Player C can play either a Skip of any color, any card of the color of Player A's Skip card, a Wild card, or, if he doesn't have a card of the current color, a Wild Draw 4. If he plays a Wild or a Wild Draw 4, he calls the color. If it's his second-to-last card, he says "Uno" before laying down the card. If he has no playable cards or chooses not to play any of the cards he has, he draws one card from the draw pile. If that card is playable, he may play it immediately (after calling "Uno" again if applicable); if it's not playable he puts it in his hand, and it's Player D's turn.
When playing the two-player version, whenever someone plays a Skip (or a Reverse, which acts as a Skip in the two-player version), it's immediately that same player's turn again.
No, you cannot put a skip card on top of another skip card in Uno.
No, you cannot stack a Skip card on top of another Skip card in Uno.
No, you cannot end a game of Uno by playing a Skip card.
No, you cannot end the game of Uno by playing a skip card.
"Do you want to pass your turn by using a skip card in Uno?"
No, you cannot put a Skip card on top of a Draw 2 card in Uno.
No, you cannot put a Skip card on top of a Draw 4 card in Uno.
No, you cannot use a Uno reverse card to skip your turn in the game.
"Do you want to use the Uno Skip Turn card to pass your turn in the game?"
These cards are from Uno.
"Do you want to play a skip card in Uno to make the next player miss their turn?"
When a player plays a Skip card in Uno, the next player in turn is skipped and loses their chance to play a card.