For example, the reader doesn’t need to read every step as Joe walks into his bathroom, brushes his teeth, combs his hair, shaves, etc. “Joe got ready for work” is sufficient.
Another example is when a character is telling another character what happened to him. Since we as the reader already know all the events he’s relating, we don’t need to read his dialogue telling his friend.
Jason Bourne related everything to other agent as he tied him up and set the house to blow up.
In the example above, we also didn’t need to follow all of Bourne’s actions as he rigged the house, because it’s not emotionally important.
However, what if the agent has information to impart while Bourne is telling the agent what happened to him? What if the agent can explain why so-and-so shot at Bourne, why such-and-such agency never existed, etc.?
In that case, show the complete dialogue between Bourne and the agent, because the information the agent gives him will cause an emotional reaction in Bourne and influence his decisions about what to do next.
Therefore, if the actions aren’t emotionally significant to the story or plot, telling is preferred. But if there will be emotionally relevant information, then go ahead and show it.