The first thing that catches my eyesught my attention in this picture is that it looks like the photo was taken indoors, as I can see some walls in the background.

I can also see a lot of sunlight coming through the windows in the background, so I suppose that the photo was sureprobably taken in the morning or afternoon.

All of them have straight, fair hair.

Two of them are wearing a long-sleeved t-shirt and jeans.

If I hadwere to take a guess, I'd say they are probably a family.

They seem to be in a house, because I can see what looks like a kitchen in the background.

Image Description of an Image

You title is technically grammatically correct but it sounds funny to me.

The photo in question -->I'm describing can be found by visiting https://breakoutenglish.com/wp-content/uploads/2021/02/family-5.jpg.

The first thing that catches my eyes in this picture is that it looks likeas if the photo was taken indoors, as I can see some walls in the background.

"To catch my eye" is a set expression.
Walls can be seen when standing outside, too.

I can also see a lot of sunlight coming through the windows in the background, so I suppose that the photo was surely taken in the morning or afternoon.

"suppose" and "surely" mean opposite things so use one or the other.

One of them seems middle-aged to me,older to me. She's maybe in her thirties.

"Middle-aged" does not refer to someone in their 30's. Please look up the words you're using before using them.

Two of them are wearing long-sleeved t-shirts and jeans.

They don't look like t-shirts to me.

If I had to take awere to guess, I'd say they are probably a family.

They seem to be in a house, because I can see what looks like a kitchen in the background.

Judging by the looks ofn their faces, I'd say they are rather focused on what the tablet is displaying.

"looks on [people's] faces" is a set expression.

I can also see a lots of sunlight coming through the windows in the background, so I supposethink that the photo was sureprobably taken in the morning or in the afternoon.

One of themThe woman in the middle seems middle-aged to me, maybe in her thirties.

The other two people are a child and a baby.

All of them have straight fair, light coloured hair.

Two of them are wearing a long-sleeved t-shirt and jeans.

They seem to be in a house, because I can see what looks like a kitchen in the background.

I'd say this with the sentence about the walls.

The first thing that catches my eyes in this picture is that it looks like the photo was taken indoors, as I can see some walls in the background.

The expression is singular: catch my eye.

I can also see a lot of sunlight coming through the windows in the background, so I suppose that the photo was surely taken in the morning or afternoon.

While correct, you are already "supposing" that the photo was taken during the day. Adding "surely" sounds repetitive.

Two of them are wearing long-sleeved t-shirts and jeans.