how many index can we use in a table?
how many fields added in per index?
The maximum number of indexes supported is 32,767, regardless of block size
Index entries have a maximum of 16 fields per index
You can define dozens of indexes per table. But that doesn't mean that you should. Each additional index on a table makes updates more expensive, not to mention maintenance activities like index compact, repair, rebuild, dump and load, etc.
Your database design should be guided by the needs of your application(s). If you run up against an architectural limit here then you have probably done something wrong, i.e. your design is very inefficient.
You may want to check out the summary of OpenEdge RDBMS limits.