Linux uses three timestamps in a file: last access time, last modification time and last change time. They are briefly described below:
To see detailed timestamps of any file in Linux file system, you can use
$ stat README.md File: `README.md' Size: 22 Blocks: 8 IO Block: 4096 regular file Device: 800h/2048d Inode: 2331722 Links: 1 Access: (0654/-rw-r-xr--) Uid: ( 500/webadmin) Gid: ( 48/ apache) Access: 2019-06-15 10:16:30.302003301 +0000 Modify: 2019-06-15 10:16:30.302003301 +0000 Change: 2019-12-28 15:51:09.906630209 +0000
Access: 2019-06-15 10:16:30.302003301 +0000 tells that the file was last accessed on 15th of June 2019 at 10:16 AM.
To change the timestamp, read article Change File Date in Linux With Touch