What timestamp means
A timestamp is the recorded date and time attached to an entry, a photo, or a file. In documentation it does quiet but essential work: it fixes when something was recorded, which is what makes an entry contemporaneous and what lets a series of entries form a datable pattern.
There is an important difference between a timestamp applied automatically when an entry is created and a date typed in by hand. A hand-entered date proves nothing about when the note was actually written; it could have been backdated. An automatic timestamp, recorded at the moment of entry, is more credible than a typed date, though it is only as reliable as the device clock that produced it.
Example: an entry that the system stamped the evening an incident occurred supports the claim that you logged it right away. A note simply headed with last Tuesday's date, typed whenever, does not carry the same assurance.
Automatic timestamps combined with a preserved edit history help a record show not just what it says but when it was logged, though how much weight any of it gets remains a jurisdiction-specific question for your attorney.