I don't know enough about your project. In addition to other answers already posted, Web services allow data consumers to access data across the internet without knowing how the data is stored or where it is stored or even the format of the storage. The contract between the client and the service is all you need to know.
If you expect that your application will be used by many systems and you don't want to expose either your data model or the logic used to access this data for whatever reason to these other systems and still want them to get some or all of the data, Web Services is a good candidate for that.
Web Services is the core of SOA. SOA allows your system to be easier to integrate and integrate with. For the service consumer, it is always easier to just use the service than to build the mechanisms for it.
Web Services are platform independent.So you could call the service to get the data regardless of the technology of the service. However, both the service consumer and the service must agree on the data exchange format, etc.
"There are currently two schools of thought in developing web services: the traditional, standards-based approach (SOAP) and conceptually simpler and the trendier new kid on the block (REST)." See Rest vs SOAP
Web Services are good choice when you accessing data on different databases since it abstracts the data sources.
Web Services is used by data stores that use NoSQL, such as Amazon SimpleDb and others. Web Services are used by Business Process Modeling tools to create processes from BPM flows.
Web Services and SOA are large subjects in IT today. There are entire books devoted to these subjects.
The site Many Videos has lots of videos on the subject.