Finding part time jobs in Eindhoven can be challenging, especially if you do not speak Dutch. Most restaurants, cafes etc. will require you to speak Dutch, but it is possible to find locations that do not, though Dutch language skills will always be a plus. Among others, the Hubble Community Cafe in the Luna building, as well as both SPAR supermarkets on Campus, employ non Dutch speakers.
Thankfully, the TU/e provides many oportunities for employment to non Dutch speakers, and also provides resources to finding employment from outside parties.
A student assistant at the TU/e is a term used for a wide variety of jobs. You can apply to be a student assistant for a course you have previously passed, helping the professor with grading or tutoring. This usually requires you to have a high (7+ depending on the course) grade from the course, but often this requirement is loosened if many assistants are required. The university will often email you about open positions in courses you have passed, but it is a good idea to speak to the professor of a course if you are interested in a assistantship.
Euflex is the employment agency of the TU/e. They provide support for applying for work at outside companies, as well as manage payroll and other employment services at the TU/e. Their website has information on employment possibilities, both full and part time, and before and after receiving your degree. They also provide a service known as Jobteaser, which is a job portal specifically for the TU/e, and a very useful resource.