The OSL 3.0 is a rather uncommon, less used open source license. It is in spirit similar to the AGPL licenses in that a usage in "external deployments" may trigger the license copyleft terms.
So in a nutshell, yes you can build a commercial software that is derived from OSL-licensed software and yes you can sell it. But as a derivative work, the software will still be subject to the OSL at large and in particular:
- you will have to redistribute the source code per section 3.
- customers that do an "external deployment" per section 5 will have to redistribute the code "to the public" per section 1.c of the OSL 3.0
- customers will have the right to change and redistribute your changes under the OSL for free, or modify further or sell these per section 1.