sohu ha, sasimi yori tenpura no hou ga tabeyasui to yoku iimasu.

は marks 祖父 as the topic of the sentence: As for my grandfather, ...

The sentence is mainly about what your grandfather tends to say, not about identifying who the speaker is. If you used が, it could sound more like you are emphasizing that he is the one who says it.

So here, 祖父は is the natural topic-setting phrase.

Yes, in a sentence like this, 祖父 usually means my grandfather.

In Japanese, when talking about your own family to other people, you often use plain family terms like:

• 祖父 = my grandfather
• 祖母 = my grandmother
• 父 = my father
• 母 = my mother

Using おじいさん for your own grandfather would usually sound less natural in this kind of context, because おじいさん is more respectful/polite and is often used for someone else’s grandfather, or for grandfather-like elderly men in general.

より marks the standard of comparison, so it means than.

Here:

• 刺身より = than sashimi

The pattern is:

• A より B のほうが C
• B is more C than A

So:

• 刺身より天ぷらのほうが食べやすい
• Tempura is easier to eat than sashimi

This is part of a very common comparison pattern:

• A より B のほうが ...

It means B is more ... than A.

Here:

• 刺身より = than sashimi
• 天ぷらのほうが = tempura, rather / tempura is the one that...
• 食べやすい = easy to eat

ほう literally means side or direction, but in this pattern it helps show which of the two things is being chosen as the stronger example.

So 天ぷらのほうが means something like tempura, rather, is easier to eat.

Because 天ぷらのほう is functioning as the subject of 食べやすい.

In other words, the sentence is saying:

• As for tempura, it is easier to eat
• compared with sashimi

So the structure is:

• 刺身より = than sashimi
• 天ぷらのほうが = tempura is the one that...
• 食べやすい = is easy to eat

The が marks what is being described by 食べやすい.

Yes, but that would mean the opposite.

Compare:

• 刺身より天ぷらのほうが食べやすい
  = Tempura is easier to eat than sashimi.

• 天ぷらより刺身のほうが食べやすい
  = Sashimi is easier to eat than tempura.

So in this pattern, the thing after より is the thing being compared against, and the thing before のほうが is the one being judged as more easy to eat.

食べやすい is made from:

• 食べ = the stem of 食べる
• やすい = easy to do

So literally it means:

• easy to eat

This is a very common pattern in Japanese:

• verb stem + やすい = easy to do
• verb stem + にくい = hard to do

Examples:

• 読みやすい = easy to read
• 分かりやすい = easy to understand
• 使いやすい = easy to use

Also, やすい behaves like an い-adjective, so it can change like one:

• 食べやすい = easy to eat
• 食べやすかった = was easy to eat
• 食べやすくない = not easy to eat

と is the quotation/content marker used with 言う.

It marks the content of what is said.

So:

• 刺身より天ぷらのほうが食べやすい と 言います
• (he) says that tempura is easier to eat than sashimi

In Japanese, と is used not only for direct quotes, but also for reported content. It does not always mean someone said those exact words word-for-word.

よく here means often.

So:

• よく言います = often says

The non-past form 言います is used because this is a habitual action, not just something happening right now. Japanese often uses the non-past for repeated or usual actions.

So the sentence means your grandfather says this regularly, as a habit.

Not necessarily.

Using と言います can report either:

• the exact words, or
• just the general idea of what someone says

Here it most naturally means the general content:

• My grandfather often says that tempura is easier to eat than sashimi.

It does not strongly imply that he always uses those exact words.

No. Normal Japanese writing usually does not put spaces between words.

So a more natural written version would be:

祖父は、刺身より天ぷらのほうが食べやすいとよく言います。

The spaces in your version are probably there just to help learners see the parts more clearly. The comma 、 and period 。 are normal, but the spaces are mainly for study purposes.