Should I accept 60K euro per year offer from Berlin ?

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Please give more details when posting questions. €60,000 is a good wage but what are the jobs?

Software Developer in Berlin.

This decides not so much on the financial aspect, but on what kind of career and life you want to have in future.
Your message gives no hint as to what your preferences are here.

My friend got an offer with 60k euro per year (job title: senior php developer). He gonna  move to Berlin with his wife. He does not know if it's enough or not because the tax is so high.

€60k/year translates to €5k/nonth (at 12 months per year) and this results in (with some assumptions about personal details) approx. €3350/month after tax and deductions.
This is more than the average German household income of around €2500/month and thus should be sufficient for a couple.

60,000 Euros is a very good wage. The question is one's expectations. Many foreigners hear of such wages and assume they will be rich and able to save 10,000 or more a year. Others are more realistic and realize that there are taxes and higher costs of living than in most 3rd world countries. Since such a wage is higher than the German national average, it is of course enough to live on comfortably. It comes down to lifestyle.  People who try to live beyond their means end up in debt whether they earn 60,000 Euros a year or a million.

Two of the biggest factors are school and accommodation. If kids are put into private international schools then it will cost 10,000 Euros or more a year! One might have a nice 4 room, 80 square meter apartment in a decent neighborhood in a large city and pay around 1500 Euros a month. Yet people from some countries like the USA are used to having a whole house with garden, something possible to find in smaller German communities but difficult in big cities. They make the mistake of thinking this is necessary in Europe as well. But one is then probably going to pay 3,000 Euros a month minimum and likely much more.

Thus even for someone with a family earning 60,000 Euros a year it will probably mean public schools – which are generally good in Germany and living in an apartment rather than a house. No problem with this situation but one should be aware of it. Another is food costs. Super markets are well stocked and rather cheap in Germany while middle and higher price ranged restaurants are not cheap. Cooking your own food and just occasionally eating out, particularly at good but cheaper places can mean spending a tenth of what one might spend eating out regularly at full price restaurants. If a small family has trouble living on 60,000 Euros a year in Germany it is because of their budget priorities rather than too little money.