i have a question about magic knight - breaker(breaker the magical warrior). does it mean that when i activate a spell, a spell counter would be placed on it or is it that spell counters could only be placed on this card by other card effects or when it is flipped summon, normal summon or special summoned as the translations which i had seen just wrote summoned

Breaker the Magical Warror only gets a Spell Counter when Normal Summoned. It does not get a Spell Counter when a Spell Card is played, or when it is Special Summoned or Flip Summoned.

Says right on the card....

Breaker the Magical Warrior
Dark/Spellcaster/4/1600/1000
When this card is Normal Summoned, put 1 Spell Counter on it (max. 1). Increase the ATK of this card by 300 points for each Spell Counter on this card. By removing 1 Spell Counter from this card, destroy 1 Spell or Trap Card on the field.

It will not get extra Spell Counter's put on it when magic cards are used...that only applies to cards that specifically say so like...

Skilled Dark Magician
Skilled White Magician
Royal Magical Library
Magical Marionette
Tower of Babel
etc

You can put more counters on Breaker, but it requires cards like Pitch Black Power Stone, which has the effect of being able to put spell counters on cards.

Yes, but only if the spell counter is already gone, you can only have 1 spell counter on breaker.