This generally means entering a property in a way that would cause physical damage.
"Force" is effort over and above what is normally needed to enter the house. For example, using a key to open the door is normal, but using a pick to “force” the lock to open without a key would be forceful entry.
“Violent” entry shows visible physical damage to the property, showing where the force was applied. For example a broken window or smashed down door.
You must take reasonable care to protect your property. If a burglar is able to gain access to your home through an unlocked door or using a spare key, there will be no signs of forcible and violent entry, so this would not be covered by a standard home insurance policy.