You can overfill your oil and overfilling your engine will oil can cause damage to the engine.
When the engine has too much oil and is overfilled the oil will get aerated or churned by the crankshaft and will turn the engine oil foamy which makes the oil unable to lubricate the engine bearings and other engine parts as it should.
As a result the engine bearings will eventually seize and/or the engine will throw a rod and be damaged.
If you overfilled your oil by 1/2 a quart or less then it is not always a cause for concern but overfilling the engine more than 1/2 a quart is bad and will damage the engine.
If you did overfill the engine with too much oil you must drain out the excess oil.
If the oil is just foamy or bubbly but it's not discolored and otherwise looks normal then it's a sign that the engine has been overfilled with too much oil.
When an engine is overfilled with too much oil it causes the oil to be mixed and churned and aerated by the crankshaft which causes the foamy appearance of the oil.
If you don't drain the excess oil out to the proper engine oil level it will eventually lead to engine bearing failure and the bearings of the engine will seize up and could even cause the engine block to break or a rod to throw through the oil pan or engine block.
Foamy engine oil cannot lubricate properly so it can harm the engine.
Overfilling your engine oil slightly such as in half a quart or less is not always a problem.
But overfilling the engine oil too much is bad and can cause engine failure so you must drain any excess engine oil to prevent engine failure which is a costly repair.