It's a way of creating an adjective from a noun. By adding 'ish' you are saying that something has the characteristics or manner or likeness of that noun. He's sixtyish in age". He's about 60. He isn't 60, but he's approximately that. She acts tomboyish". She acts like a tomboy. "I'm feeling a bit sickish". I feel a bit sick. I'm not sure if I am exactly sick, but my symptoms seem that way. For arrayish, meaning will depend on context. From my own computing background one possibility is you are describing some structure that has the characteristics or property of an array. "This data structure is somewhat arrayish". This is very informal, but that's how I would understand you ..... if it were a math or computing context. Other contexts will mean other meanings. It will depend on what meaning of 'array' you are using.

"Array-ish" isn't a common construction - I've never seen it before - but this construction can be made with any almost noun. This "-ish" suffix on a noun means "like, having the characteristics of" - "He was a young-looking man, almost boyish," - so something that was "array-ish" would have the characteristics of an array - "The objects laid out in straight rows and columns looked array-ish." "Array" has a few different meanings. It can mean "finery, expensive clothing" - "She entered the ballroom resplendent in her fine array," - or it can mean "range or variety" - "We have a wide array of options for you to choose from," - or "an ordered series or arrangement" - "An array of solar panels provides the electrical power." I'm not sure how either of the first two meanings could work with "-ish," so I think this is probably a use of third meaning - "The disorderly ranks of troops struggled to form up into something that looked array-ish." I've never seen it, and I'd never use it; but that's what I think "array-ish" probably means. :)