If we have a table which is accessed by multiple users and two or more user's are simultaniously trying to modify the table. Then what happens and how can we manage such situations?

if one user is going to modify the table he will be aquired lock on that particular row of that table and it will be released to the other user whose is trying ot modify the same table after the modifications are commited by the first user. or else, we can handle the situations using no wait option

Could you please elaborate how can we do it with no wait option.

There are two ways of changing the rows in particular table.
One to delete the row
Second to modify/Change the data of row in table.
In every case we opt for exclusive locks

So when one user has exclusive lock then another user can’t share that information unless first user releases that locks.

Another type of lock is shared lock, which is used when two or more users share the same information for reading purpose (No change in the database).

Simultaneously modification of same table by two or more users cause Oracle server to go into hang state, to avoid such a state first user who used dml statement should issue commit or rollback comand.

Possible solutions also consist of that the Oracle DBA could create procedure which states ''''' for update of column_name nowait ''' command.

Regards
Dharmendra Jaiswal