Is it helpful in defending,or what is it helping XD i don't know

Dexterity is good for accuracy and critical strike. Increasing dexterity increases the chance that your pet will not miss when attacking, and will also increase the chance for your pet to exploit a weak spot on the enemy and deal more damage.

Oh ok thanks, is there anything for defence?

It depends on what kind of defence you're after.

HP = Health, more health means a pet can take more hits
Mana = there are some Proficiency trees that have abilities that buff a pet's stats temporarily

Strength = increases a pets physical damage and mitigation (or + physical attack, + physical defence)
Intelligence = increases a pets magical damage and mitigation (or + magic attack, + magic defence)

Dexterity = crits and accuracy, as mentioned
Agility = Increases physical and magical mitigation, increases chance of avoiding enemy attacks, increases quickness (speed)
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Most pets will use a combo of their selected 'attack' stat (Str or Int), Agility, and HP in assorted amounts as 'defence', added on to by their equipment.

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Equipment: All pieces of equipment have both set boosts based on
- Type (Relic/armour/bracelet)
- Level (Tattered/Dull/Faded/etc., or "pet must be at least level ___ to use this item" stat, higher level pets able to use the better items)
- Rarity (common/uncommon/rare/epic/legendary/mythical, higher rarity means better stats.)
- Class (Evoker/Illusionist/Warden/etc. Each class has a different setup. Crusader items are always Str/Int, Illusionist are always Int/Agi)
- Damage (Relics/shields either give Strength, Magical, or Split attack. This does not coincide with the relic's Class. It's recommended that one uses relics with a damage output that matches the Class of the relic and stats of the pet using it)

- Percents (all pieces of equipment have different percent boosts on their physical mitigation, magical mitigation, crit chances, avoidance chance, and accuracy. These percent bonuses scale with Rarity of an item. They're pretty minor but present. (The highest percent increase I know of is Vylexul's equipment, which gives him some +2.00%'s. But Vylexul, being Vylexul, is an outlier, so let's not count him. He's more like a god in sylesti form than anything) The general highest that I know of is 1.50% increase.

(on a pet's page,
HP/Mana/Exp are bars presented in red, blue and purple
Level is black text
Phys and Magi damage is blue text
Str/Int/Dex/Agi are purple text
Percentages are Orange)

Scathreoite gave a nice, detailed answer. There are a lot of different factors that contribute to better defense. Really try hard to get as good equipment as possible. At your level, there should be quite a bit cheap equipment on the trade broker.

But the short version is: Health & Agility are best for tanks (defenders). Health can take a lot of attacks and Agility causes a lot of attacks to miss.

For pure blocking power, high int reduces magic attacks and high strength reduces physical attacks. (In your stats this is physical and magical mitigation.)