Error: remaining part of expression cannot be interpreted

What causes this issue?

The syntax check could not interpret part of your entry.

System Response

The cursor shows the start of the expression that could not be
interpreted.

How to fix this error?

Check the separator characters in your entry. In a condition, ensure
that the individual parts of the condition are linked with logical
operators such as AND and OR. In actions, the individual parts of the
action must be separated from each other by a comma (',').
In constraints, if you enter several expressions in the sections
RESTRICTIONS: or CONDITION:, the individual expressions must be
separated by a comma.
You should also note that the only decimal point allowed in figures is
a period ('.').

Error message extract from SAP system. Copyright SAP SE.