There are several Araniella species found in the Netherlands but two of them are very similar and not to tell apart from a photo: Araniella cucurbitina and Araniella opisthographa. 
The photos show either one of them.
They are a pale yellowish green in colour and have a red mark under the abdomen.
Females grow up to 8 mm, males only up to 5 mm. 

In my yard, Hilversum, The Netherlands, 25 May 2020