The UML does not provide syntax as in a programming language but it provides syntax in terms of notation and diagrams to visually define your system. 

The UML is not visual programming language, but a visual modeling language, and is a tool or a repository specification, but a modeling language specification and is a process but enables processes (OReilly & Associates Inc., 1998).  The UML may be used in a variety of ways to support a software development methodology (such as Rational Unified Process) ¨C but in itself it does not specify that methodology or process.

Utility of the UML

The UML is an evolutionary general-purpose, broadly applicable, tool-supported and industry-standardized modeling language.  It applies to a multitude of different types of systems, domains, and methods or processes (OReilly & Associates Inc., 1998).  OReilly & Associates Inc., continued to define the strengths of the UML as: 

As a general-purpose modeling language, it focuses on a core set of concepts for cquiring, sharing and utilizing knowledge coupled with extensibility mechanisms. 
As a broadly applicable modeling language, it may be applied to different types of  systems (software and non-software), domains (business versus software), and methods or processes.
As a tool-supported modeling language, tools are readily available to support the application of the language to specify, visualize, construct, and document systems.
As an industry-standardized modeling language, it is not a proprietary and closed language but an open and fully extensible industry-recognized language