This summary is not the rule. The rule text controls.
This law explains when a regular citizen, not a police officer, can legally arrest someone else. It covers three different situations where a private arrest is allowed.
First, you can arrest someone if you see them commit a crime right in front of you. It does not matter if the crime is big or small, as long as you witness it happening or being attempted.
Second, you can arrest someone if they actually committed a felony, even if you did not see them do it. A felony is a serious crime, like robbery or assault with a weapon.
Third, you can arrest someone if a felony really happened and you have good reason to believe that person did it. This means you need real evidence or solid reasons for your belief, not just a guess or suspicion. This last situation carries more risk, because if you are wrong about the crime happening or about who did it, you could face legal trouble yourself for making a false arrest.